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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2011, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.lang; | ||
| 27 | |||
| 28 | import java.io.PrintStream; | ||
| 29 | import java.util.Arrays; | ||
| 30 | import sun.misc.VM; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * A thread group represents a set of threads. In addition, a thread | ||
| 34 | * group can also include other thread groups. The thread groups form | ||
| 35 | * a tree in which every thread group except the initial thread group | ||
| 36 | * has a parent. | ||
| 37 | * <p> | ||
| 38 | * A thread is allowed to access information about its own thread | ||
| 39 | * group, but not to access information about its thread group's | ||
| 40 | * parent thread group or any other thread groups. | ||
| 41 | * | ||
| 42 | * @author unascribed | ||
| 43 | * @since JDK1.0 | ||
| 44 | */ | ||
| 45 | /* The locking strategy for this code is to try to lock only one level of the | ||
| 46 | * tree wherever possible, but otherwise to lock from the bottom up. | ||
| 47 | * That is, from child thread groups to parents. | ||
| 48 | * This has the advantage of limiting the number of locks that need to be held | ||
| 49 | * and in particular avoids having to grab the lock for the root thread group, | ||
| 50 | * (or a global lock) which would be a source of contention on a | ||
| 51 | * multi-processor system with many thread groups. | ||
| 52 | * This policy often leads to taking a snapshot of the state of a thread group | ||
| 53 | * and working off of that snapshot, rather than holding the thread group locked | ||
| 54 | * while we work on the children. | ||
| 55 | */ | ||
| 56 | public | ||
| 57 | class ThreadGroup implements Thread.UncaughtExceptionHandler { | ||
| 58 | private final ThreadGroup parent; | ||
| 59 | String name; | ||
| 60 | int maxPriority; | ||
| 61 | boolean destroyed; | ||
| 62 | boolean daemon; | ||
| 63 | boolean vmAllowSuspension; | ||
| 64 | |||
| 65 | int nUnstartedThreads = 0; | ||
| 66 | int nthreads; | ||
| 67 | Thread threads[]; | ||
| 68 | |||
| 69 | int ngroups; | ||
| 70 | ThreadGroup groups[]; | ||
| 71 | |||
| 72 | /** | ||
| 73 | * Creates an empty Thread group that is not in any Thread group. | ||
| 74 | * This method is used to create the system Thread group. | ||
| 75 | */ | ||
| 76 | private ThreadGroup() { // called from C code | ||
| 77 | this.name = "system"; | ||
| 78 | this.maxPriority = Thread.MAX_PRIORITY; | ||
| 79 | this.parent = null; | ||
| 80 | } | ||
| 81 | |||
| 82 | /** | ||
| 83 | * Constructs a new thread group. The parent of this new group is | ||
| 84 | * the thread group of the currently running thread. | ||
| 85 | * <p> | ||
| 86 | * The <code>checkAccess</code> method of the parent thread group is | ||
| 87 | * called with no arguments; this may result in a security exception. | ||
| 88 | * | ||
| 89 | * @param name the name of the new thread group. | ||
| 90 | * @exception SecurityException if the current thread cannot create a | ||
| 91 | * thread in the specified thread group. | ||
| 92 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 93 | * @since JDK1.0 | ||
| 94 | */ | ||
| 95 | public ThreadGroup(String name) { | ||
| 96 | this(Thread.currentThread().getThreadGroup(), name); | ||
| 97 | } | ||
| 98 | |||
| 99 | /** | ||
| 100 | * Creates a new thread group. The parent of this new group is the | ||
| 101 | * specified thread group. | ||
| 102 | * <p> | ||
| 103 | * The <code>checkAccess</code> method of the parent thread group is | ||
| 104 | * called with no arguments; this may result in a security exception. | ||
| 105 | * | ||
| 106 | * @param parent the parent thread group. | ||
| 107 | * @param name the name of the new thread group. | ||
| 108 | * @exception NullPointerException if the thread group argument is | ||
| 109 | * <code>null</code>. | ||
| 110 | * @exception SecurityException if the current thread cannot create a | ||
| 111 | * thread in the specified thread group. | ||
| 112 | * @see java.lang.SecurityException | ||
| 113 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 114 | * @since JDK1.0 | ||
| 115 | */ | ||
| 116 | public ThreadGroup(ThreadGroup parent, String name) { | ||
| 117 | this(checkParentAccess(parent), parent, name); | ||
| 118 | } | ||
| 119 | |||
| 120 | private ThreadGroup(Void unused, ThreadGroup parent, String name) { | ||
| 121 | this.name = name; | ||
| 122 | this.maxPriority = parent.maxPriority; | ||
| 123 | this.daemon = parent.daemon; | ||
| 124 | this.vmAllowSuspension = parent.vmAllowSuspension; | ||
| 125 | this.parent = parent; | ||
| 126 | parent.add(this); | ||
| 127 | } | ||
| 128 | |||
| 129 | /* | ||
| 130 | * @throws NullPointerException if the parent argument is {@code null} | ||
| 131 | * @throws SecurityException if the current thread cannot create a | ||
| 132 | * thread in the specified thread group. | ||
| 133 | */ | ||
| 134 | private static Void checkParentAccess(ThreadGroup parent) { | ||
| 135 | parent.checkAccess(); | ||
| 136 | return null; | ||
| 137 | } | ||
| 138 | |||
| 139 | /** | ||
| 140 | * Returns the name of this thread group. | ||
| 141 | * | ||
| 142 | * @return the name of this thread group. | ||
| 143 | * @since JDK1.0 | ||
| 144 | */ | ||
| 145 | public final String getName() { | ||
| 146 | return name; | ||
| 147 | } | ||
| 148 | |||
| 149 | /** | ||
| 150 | * Returns the parent of this thread group. | ||
| 151 | * <p> | ||
| 152 | * First, if the parent is not <code>null</code>, the | ||
| 153 | * <code>checkAccess</code> method of the parent thread group is | ||
| 154 | * called with no arguments; this may result in a security exception. | ||
| 155 | * | ||
| 156 | * @return the parent of this thread group. The top-level thread group | ||
| 157 | * is the only thread group whose parent is <code>null</code>. | ||
| 158 | * @exception SecurityException if the current thread cannot modify | ||
| 159 | * this thread group. | ||
| 160 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 161 | * @see java.lang.SecurityException | ||
| 162 | * @see java.lang.RuntimePermission | ||
| 163 | * @since JDK1.0 | ||
| 164 | */ | ||
| 165 | public final ThreadGroup getParent() { | ||
| 166 | if (parent != null) | ||
| 167 | parent.checkAccess(); | ||
| 168 | return parent; | ||
| 169 | } | ||
| 170 | |||
| 171 | /** | ||
| 172 | * Returns the maximum priority of this thread group. Threads that are | ||
| 173 | * part of this group cannot have a higher priority than the maximum | ||
| 174 | * priority. | ||
| 175 | * | ||
| 176 | * @return the maximum priority that a thread in this thread group | ||
| 177 | * can have. | ||
| 178 | * @see #setMaxPriority | ||
| 179 | * @since JDK1.0 | ||
| 180 | */ | ||
| 181 | public final int getMaxPriority() { | ||
| 182 | return maxPriority; | ||
| 183 | } | ||
| 184 | |||
| 185 | /** | ||
| 186 | * Tests if this thread group is a daemon thread group. A | ||
| 187 | * daemon thread group is automatically destroyed when its last | ||
| 188 | * thread is stopped or its last thread group is destroyed. | ||
| 189 | * | ||
| 190 | * @return <code>true</code> if this thread group is a daemon thread group; | ||
| 191 | * <code>false</code> otherwise. | ||
| 192 | * @since JDK1.0 | ||
| 193 | */ | ||
| 194 | public final boolean isDaemon() { | ||
| 195 | return daemon; | ||
| 196 | } | ||
| 197 | |||
| 198 | /** | ||
| 199 | * Tests if this thread group has been destroyed. | ||
| 200 | * | ||
| 201 | * @return true if this object is destroyed | ||
| 202 | * @since JDK1.1 | ||
| 203 | */ | ||
| 204 | public synchronized boolean isDestroyed() { | ||
| 205 | return destroyed; | ||
| 206 | } | ||
| 207 | |||
| 208 | /** | ||
| 209 | * Changes the daemon status of this thread group. | ||
| 210 | * <p> | ||
| 211 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 212 | * called with no arguments; this may result in a security exception. | ||
| 213 | * <p> | ||
| 214 | * A daemon thread group is automatically destroyed when its last | ||
| 215 | * thread is stopped or its last thread group is destroyed. | ||
| 216 | * | ||
| 217 | * @param daemon if <code>true</code>, marks this thread group as | ||
| 218 | * a daemon thread group; otherwise, marks this | ||
| 219 | * thread group as normal. | ||
| 220 | * @exception SecurityException if the current thread cannot modify | ||
| 221 | * this thread group. | ||
| 222 | * @see java.lang.SecurityException | ||
| 223 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 224 | * @since JDK1.0 | ||
| 225 | */ | ||
| 226 | public final void setDaemon(boolean daemon) { | ||
| 227 | checkAccess(); | ||
| 228 | this.daemon = daemon; | ||
| 229 | } | ||
| 230 | |||
| 231 | /** | ||
| 232 | * Sets the maximum priority of the group. Threads in the thread | ||
| 233 | * group that already have a higher priority are not affected. | ||
| 234 | * <p> | ||
| 235 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 236 | * called with no arguments; this may result in a security exception. | ||
| 237 | * <p> | ||
| 238 | * If the <code>pri</code> argument is less than | ||
| 239 | * {@link Thread#MIN_PRIORITY} or greater than | ||
| 240 | * {@link Thread#MAX_PRIORITY}, the maximum priority of the group | ||
| 241 | * remains unchanged. | ||
| 242 | * <p> | ||
| 243 | * Otherwise, the priority of this ThreadGroup object is set to the | ||
| 244 | * smaller of the specified <code>pri</code> and the maximum permitted | ||
| 245 | * priority of the parent of this thread group. (If this thread group | ||
| 246 | * is the system thread group, which has no parent, then its maximum | ||
| 247 | * priority is simply set to <code>pri</code>.) Then this method is | ||
| 248 | * called recursively, with <code>pri</code> as its argument, for | ||
| 249 | * every thread group that belongs to this thread group. | ||
| 250 | * | ||
| 251 | * @param pri the new priority of the thread group. | ||
| 252 | * @exception SecurityException if the current thread cannot modify | ||
| 253 | * this thread group. | ||
| 254 | * @see #getMaxPriority | ||
| 255 | * @see java.lang.SecurityException | ||
| 256 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 257 | * @since JDK1.0 | ||
| 258 | */ | ||
| 259 | public final void setMaxPriority(int pri) { | ||
| 260 | int ngroupsSnapshot; | ||
| 261 | ThreadGroup[] groupsSnapshot; | ||
| 262 | synchronized (this) { | ||
| 263 | checkAccess(); | ||
| 264 | if (pri < Thread.MIN_PRIORITY || pri > Thread.MAX_PRIORITY) { | ||
| 265 | return; | ||
| 266 | } | ||
| 267 | maxPriority = (parent != null) ? Math.min(pri, parent.maxPriority) : pri; | ||
| 268 | ngroupsSnapshot = ngroups; | ||
| 269 | if (groups != null) { | ||
| 270 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 271 | } else { | ||
| 272 | groupsSnapshot = null; | ||
| 273 | } | ||
| 274 | } | ||
| 275 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 276 | groupsSnapshot[i].setMaxPriority(pri); | ||
| 277 | } | ||
| 278 | } | ||
| 279 | |||
| 280 | /** | ||
| 281 | * Tests if this thread group is either the thread group | ||
| 282 | * argument or one of its ancestor thread groups. | ||
| 283 | * | ||
| 284 | * @param g a thread group. | ||
| 285 | * @return <code>true</code> if this thread group is the thread group | ||
| 286 | * argument or one of its ancestor thread groups; | ||
| 287 | * <code>false</code> otherwise. | ||
| 288 | * @since JDK1.0 | ||
| 289 | */ | ||
| 290 | public final boolean parentOf(ThreadGroup g) { | ||
| 291 | for (; g != null ; g = g.parent) { | ||
| 292 | if (g == this) { | ||
| 293 | return true; | ||
| 294 | } | ||
| 295 | } | ||
| 296 | return false; | ||
| 297 | } | ||
| 298 | |||
| 299 | /** | ||
| 300 | * Determines if the currently running thread has permission to | ||
| 301 | * modify this thread group. | ||
| 302 | * <p> | ||
| 303 | * If there is a security manager, its <code>checkAccess</code> method | ||
| 304 | * is called with this thread group as its argument. This may result | ||
| 305 | * in throwing a <code>SecurityException</code>. | ||
| 306 | * | ||
| 307 | * @exception SecurityException if the current thread is not allowed to | ||
| 308 | * access this thread group. | ||
| 309 | * @see java.lang.SecurityManager#checkAccess(java.lang.ThreadGroup) | ||
| 310 | * @since JDK1.0 | ||
| 311 | */ | ||
| 312 | public final void checkAccess() { | ||
| 313 | SecurityManager security = System.getSecurityManager(); | ||
| 314 | if (security != null) { | ||
| 315 | security.checkAccess(this); | ||
| 316 | } | ||
| 317 | } | ||
| 318 | |||
| 319 | /** | ||
| 320 | * Returns an estimate of the number of active threads in this thread | ||
| 321 | * group and its subgroups. Recursively iterates over all subgroups in | ||
| 322 | * this thread group. | ||
| 323 | * | ||
| 324 | * <p> The value returned is only an estimate because the number of | ||
| 325 | * threads may change dynamically while this method traverses internal | ||
| 326 | * data structures, and might be affected by the presence of certain | ||
| 327 | * system threads. This method is intended primarily for debugging | ||
| 328 | * and monitoring purposes. | ||
| 329 | * | ||
| 330 | * @return an estimate of the number of active threads in this thread | ||
| 331 | * group and in any other thread group that has this thread | ||
| 332 | * group as an ancestor | ||
| 333 | * | ||
| 334 | * @since JDK1.0 | ||
| 335 | */ | ||
| 336 | public int activeCount() { | ||
| 337 | int result; | ||
| 338 | // Snapshot sub-group data so we don't hold this lock | ||
| 339 | // while our children are computing. | ||
| 340 | int ngroupsSnapshot; | ||
| 341 | ThreadGroup[] groupsSnapshot; | ||
| 342 | synchronized (this) { | ||
| 343 | if (destroyed) { | ||
| 344 | return 0; | ||
| 345 | } | ||
| 346 | result = nthreads; | ||
| 347 | ngroupsSnapshot = ngroups; | ||
| 348 | if (groups != null) { | ||
| 349 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 350 | } else { | ||
| 351 | groupsSnapshot = null; | ||
| 352 | } | ||
| 353 | } | ||
| 354 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 355 | result += groupsSnapshot[i].activeCount(); | ||
| 356 | } | ||
| 357 | return result; | ||
| 358 | } | ||
| 359 | |||
| 360 | /** | ||
| 361 | * Copies into the specified array every active thread in this | ||
| 362 | * thread group and its subgroups. | ||
| 363 | * | ||
| 364 | * <p> An invocation of this method behaves in exactly the same | ||
| 365 | * way as the invocation | ||
| 366 | * | ||
| 367 | * <blockquote> | ||
| 368 | * {@linkplain #enumerate(Thread[], boolean) enumerate}{@code (list, true)} | ||
| 369 | * </blockquote> | ||
| 370 | * | ||
| 371 | * @param list | ||
| 372 | * an array into which to put the list of threads | ||
| 373 | * | ||
| 374 | * @return the number of threads put into the array | ||
| 375 | * | ||
| 376 | * @throws SecurityException | ||
| 377 | * if {@linkplain #checkAccess checkAccess} determines that | ||
| 378 | * the current thread cannot access this thread group | ||
| 379 | * | ||
| 380 | * @since JDK1.0 | ||
| 381 | */ | ||
| 382 | public int enumerate(Thread list[]) { | ||
| 383 | checkAccess(); | ||
| 384 | return enumerate(list, 0, true); | ||
| 385 | } | ||
| 386 | |||
| 387 | /** | ||
| 388 | * Copies into the specified array every active thread in this | ||
| 389 | * thread group. If {@code recurse} is {@code true}, | ||
| 390 | * this method recursively enumerates all subgroups of this | ||
| 391 | * thread group and references to every active thread in these | ||
| 392 | * subgroups are also included. If the array is too short to | ||
| 393 | * hold all the threads, the extra threads are silently ignored. | ||
| 394 | * | ||
| 395 | * <p> An application might use the {@linkplain #activeCount activeCount} | ||
| 396 | * method to get an estimate of how big the array should be, however | ||
| 397 | * <i>if the array is too short to hold all the threads, the extra threads | ||
| 398 | * are silently ignored.</i> If it is critical to obtain every active | ||
| 399 | * thread in this thread group, the caller should verify that the returned | ||
| 400 | * int value is strictly less than the length of {@code list}. | ||
| 401 | * | ||
| 402 | * <p> Due to the inherent race condition in this method, it is recommended | ||
| 403 | * that the method only be used for debugging and monitoring purposes. | ||
| 404 | * | ||
| 405 | * @param list | ||
| 406 | * an array into which to put the list of threads | ||
| 407 | * | ||
| 408 | * @param recurse | ||
| 409 | * if {@code true}, recursively enumerate all subgroups of this | ||
| 410 | * thread group | ||
| 411 | * | ||
| 412 | * @return the number of threads put into the array | ||
| 413 | * | ||
| 414 | * @throws SecurityException | ||
| 415 | * if {@linkplain #checkAccess checkAccess} determines that | ||
| 416 | * the current thread cannot access this thread group | ||
| 417 | * | ||
| 418 | * @since JDK1.0 | ||
| 419 | */ | ||
| 420 | public int enumerate(Thread list[], boolean recurse) { | ||
| 421 | checkAccess(); | ||
| 422 | return enumerate(list, 0, recurse); | ||
| 423 | } | ||
| 424 | |||
| 425 | private int enumerate(Thread list[], int n, boolean recurse) { | ||
| 426 | int ngroupsSnapshot = 0; | ||
| 427 | ThreadGroup[] groupsSnapshot = null; | ||
| 428 | synchronized (this) { | ||
| 429 | if (destroyed) { | ||
| 430 | return 0; | ||
| 431 | } | ||
| 432 | int nt = nthreads; | ||
| 433 | if (nt > list.length - n) { | ||
| 434 | nt = list.length - n; | ||
| 435 | } | ||
| 436 | for (int i = 0; i < nt; i++) { | ||
| 437 | if (threads[i].isAlive()) { | ||
| 438 | list[n++] = threads[i]; | ||
| 439 | } | ||
| 440 | } | ||
| 441 | if (recurse) { | ||
| 442 | ngroupsSnapshot = ngroups; | ||
| 443 | if (groups != null) { | ||
| 444 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 445 | } else { | ||
| 446 | groupsSnapshot = null; | ||
| 447 | } | ||
| 448 | } | ||
| 449 | } | ||
| 450 | if (recurse) { | ||
| 451 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 452 | n = groupsSnapshot[i].enumerate(list, n, true); | ||
| 453 | } | ||
| 454 | } | ||
| 455 | return n; | ||
| 456 | } | ||
| 457 | |||
| 458 | /** | ||
| 459 | * Returns an estimate of the number of active groups in this | ||
| 460 | * thread group and its subgroups. Recursively iterates over | ||
| 461 | * all subgroups in this thread group. | ||
| 462 | * | ||
| 463 | * <p> The value returned is only an estimate because the number of | ||
| 464 | * thread groups may change dynamically while this method traverses | ||
| 465 | * internal data structures. This method is intended primarily for | ||
| 466 | * debugging and monitoring purposes. | ||
| 467 | * | ||
| 468 | * @return the number of active thread groups with this thread group as | ||
| 469 | * an ancestor | ||
| 470 | * | ||
| 471 | * @since JDK1.0 | ||
| 472 | */ | ||
| 473 | public int activeGroupCount() { | ||
| 474 | int ngroupsSnapshot; | ||
| 475 | ThreadGroup[] groupsSnapshot; | ||
| 476 | synchronized (this) { | ||
| 477 | if (destroyed) { | ||
| 478 | return 0; | ||
| 479 | } | ||
| 480 | ngroupsSnapshot = ngroups; | ||
| 481 | if (groups != null) { | ||
| 482 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 483 | } else { | ||
| 484 | groupsSnapshot = null; | ||
| 485 | } | ||
| 486 | } | ||
| 487 | int n = ngroupsSnapshot; | ||
| 488 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 489 | n += groupsSnapshot[i].activeGroupCount(); | ||
| 490 | } | ||
| 491 | return n; | ||
| 492 | } | ||
| 493 | |||
| 494 | /** | ||
| 495 | * Copies into the specified array references to every active | ||
| 496 | * subgroup in this thread group and its subgroups. | ||
| 497 | * | ||
| 498 | * <p> An invocation of this method behaves in exactly the same | ||
| 499 | * way as the invocation | ||
| 500 | * | ||
| 501 | * <blockquote> | ||
| 502 | * {@linkplain #enumerate(ThreadGroup[], boolean) enumerate}{@code (list, true)} | ||
| 503 | * </blockquote> | ||
| 504 | * | ||
| 505 | * @param list | ||
| 506 | * an array into which to put the list of thread groups | ||
| 507 | * | ||
| 508 | * @return the number of thread groups put into the array | ||
| 509 | * | ||
| 510 | * @throws SecurityException | ||
| 511 | * if {@linkplain #checkAccess checkAccess} determines that | ||
| 512 | * the current thread cannot access this thread group | ||
| 513 | * | ||
| 514 | * @since JDK1.0 | ||
| 515 | */ | ||
| 516 | public int enumerate(ThreadGroup list[]) { | ||
| 517 | checkAccess(); | ||
| 518 | return enumerate(list, 0, true); | ||
| 519 | } | ||
| 520 | |||
| 521 | /** | ||
| 522 | * Copies into the specified array references to every active | ||
| 523 | * subgroup in this thread group. If {@code recurse} is | ||
| 524 | * {@code true}, this method recursively enumerates all subgroups of this | ||
| 525 | * thread group and references to every active thread group in these | ||
| 526 | * subgroups are also included. | ||
| 527 | * | ||
| 528 | * <p> An application might use the | ||
| 529 | * {@linkplain #activeGroupCount activeGroupCount} method to | ||
| 530 | * get an estimate of how big the array should be, however <i>if the | ||
| 531 | * array is too short to hold all the thread groups, the extra thread | ||
| 532 | * groups are silently ignored.</i> If it is critical to obtain every | ||
| 533 | * active subgroup in this thread group, the caller should verify that | ||
| 534 | * the returned int value is strictly less than the length of | ||
| 535 | * {@code list}. | ||
| 536 | * | ||
| 537 | * <p> Due to the inherent race condition in this method, it is recommended | ||
| 538 | * that the method only be used for debugging and monitoring purposes. | ||
| 539 | * | ||
| 540 | * @param list | ||
| 541 | * an array into which to put the list of thread groups | ||
| 542 | * | ||
| 543 | * @param recurse | ||
| 544 | * if {@code true}, recursively enumerate all subgroups | ||
| 545 | * | ||
| 546 | * @return the number of thread groups put into the array | ||
| 547 | * | ||
| 548 | * @throws SecurityException | ||
| 549 | * if {@linkplain #checkAccess checkAccess} determines that | ||
| 550 | * the current thread cannot access this thread group | ||
| 551 | * | ||
| 552 | * @since JDK1.0 | ||
| 553 | */ | ||
| 554 | public int enumerate(ThreadGroup list[], boolean recurse) { | ||
| 555 | checkAccess(); | ||
| 556 | return enumerate(list, 0, recurse); | ||
| 557 | } | ||
| 558 | |||
| 559 | private int enumerate(ThreadGroup list[], int n, boolean recurse) { | ||
| 560 | int ngroupsSnapshot = 0; | ||
| 561 | ThreadGroup[] groupsSnapshot = null; | ||
| 562 | synchronized (this) { | ||
| 563 | if (destroyed) { | ||
| 564 | return 0; | ||
| 565 | } | ||
| 566 | int ng = ngroups; | ||
| 567 | if (ng > list.length - n) { | ||
| 568 | ng = list.length - n; | ||
| 569 | } | ||
| 570 | if (ng > 0) { | ||
| 571 | System.arraycopy(groups, 0, list, n, ng); | ||
| 572 | n += ng; | ||
| 573 | } | ||
| 574 | if (recurse) { | ||
| 575 | ngroupsSnapshot = ngroups; | ||
| 576 | if (groups != null) { | ||
| 577 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 578 | } else { | ||
| 579 | groupsSnapshot = null; | ||
| 580 | } | ||
| 581 | } | ||
| 582 | } | ||
| 583 | if (recurse) { | ||
| 584 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 585 | n = groupsSnapshot[i].enumerate(list, n, true); | ||
| 586 | } | ||
| 587 | } | ||
| 588 | return n; | ||
| 589 | } | ||
| 590 | |||
| 591 | /** | ||
| 592 | * Stops all threads in this thread group. | ||
| 593 | * <p> | ||
| 594 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 595 | * called with no arguments; this may result in a security exception. | ||
| 596 | * <p> | ||
| 597 | * This method then calls the <code>stop</code> method on all the | ||
| 598 | * threads in this thread group and in all of its subgroups. | ||
| 599 | * | ||
| 600 | * @exception SecurityException if the current thread is not allowed | ||
| 601 | * to access this thread group or any of the threads in | ||
| 602 | * the thread group. | ||
| 603 | * @see java.lang.SecurityException | ||
| 604 | * @see java.lang.Thread#stop() | ||
| 605 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 606 | * @since JDK1.0 | ||
| 607 | * @deprecated This method is inherently unsafe. See | ||
| 608 | * {@link Thread#stop} for details. | ||
| 609 | */ | ||
| 610 | @Deprecated | ||
| 611 | public final void stop() { | ||
| 612 | if (stopOrSuspend(false)) | ||
| 613 | Thread.currentThread().stop(); | ||
| 614 | } | ||
| 615 | |||
| 616 | /** | ||
| 617 | * Interrupts all threads in this thread group. | ||
| 618 | * <p> | ||
| 619 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 620 | * called with no arguments; this may result in a security exception. | ||
| 621 | * <p> | ||
| 622 | * This method then calls the <code>interrupt</code> method on all the | ||
| 623 | * threads in this thread group and in all of its subgroups. | ||
| 624 | * | ||
| 625 | * @exception SecurityException if the current thread is not allowed | ||
| 626 | * to access this thread group or any of the threads in | ||
| 627 | * the thread group. | ||
| 628 | * @see java.lang.Thread#interrupt() | ||
| 629 | * @see java.lang.SecurityException | ||
| 630 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 631 | * @since 1.2 | ||
| 632 | */ | ||
| 633 | public final void interrupt() { | ||
| 634 | int ngroupsSnapshot; | ||
| 635 | ThreadGroup[] groupsSnapshot; | ||
| 636 | synchronized (this) { | ||
| 637 | checkAccess(); | ||
| 638 | for (int i = 0 ; i < nthreads ; i++) { | ||
| 639 | threads[i].interrupt(); | ||
| 640 | } | ||
| 641 | ngroupsSnapshot = ngroups; | ||
| 642 | if (groups != null) { | ||
| 643 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 644 | } else { | ||
| 645 | groupsSnapshot = null; | ||
| 646 | } | ||
| 647 | } | ||
| 648 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 649 | groupsSnapshot[i].interrupt(); | ||
| 650 | } | ||
| 651 | } | ||
| 652 | |||
| 653 | /** | ||
| 654 | * Suspends all threads in this thread group. | ||
| 655 | * <p> | ||
| 656 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 657 | * called with no arguments; this may result in a security exception. | ||
| 658 | * <p> | ||
| 659 | * This method then calls the <code>suspend</code> method on all the | ||
| 660 | * threads in this thread group and in all of its subgroups. | ||
| 661 | * | ||
| 662 | * @exception SecurityException if the current thread is not allowed | ||
| 663 | * to access this thread group or any of the threads in | ||
| 664 | * the thread group. | ||
| 665 | * @see java.lang.Thread#suspend() | ||
| 666 | * @see java.lang.SecurityException | ||
| 667 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 668 | * @since JDK1.0 | ||
| 669 | * @deprecated This method is inherently deadlock-prone. See | ||
| 670 | * {@link Thread#suspend} for details. | ||
| 671 | */ | ||
| 672 | @Deprecated | ||
| 673 | public final void suspend() { | ||
| 674 | if (stopOrSuspend(true)) | ||
| 675 | Thread.currentThread().suspend(); | ||
| 676 | } | ||
| 677 | |||
| 678 | /** | ||
| 679 | * Helper method: recursively stops or suspends (as directed by the | ||
| 680 | * boolean argument) all of the threads in this thread group and its | ||
| 681 | * subgroups, except the current thread. This method returns true | ||
| 682 | * if (and only if) the current thread is found to be in this thread | ||
| 683 | * group or one of its subgroups. | ||
| 684 | */ | ||
| 685 | private boolean stopOrSuspend(boolean suspend) { | ||
| 686 | boolean suicide = false; | ||
| 687 | Thread us = Thread.currentThread(); | ||
| 688 | int ngroupsSnapshot; | ||
| 689 | ThreadGroup[] groupsSnapshot = null; | ||
| 690 | synchronized (this) { | ||
| 691 | checkAccess(); | ||
| 692 | for (int i = 0 ; i < nthreads ; i++) { | ||
| 693 | if (threads[i]==us) | ||
| 694 | suicide = true; | ||
| 695 | else if (suspend) | ||
| 696 | threads[i].suspend(); | ||
| 697 | else | ||
| 698 | threads[i].stop(); | ||
| 699 | } | ||
| 700 | |||
| 701 | ngroupsSnapshot = ngroups; | ||
| 702 | if (groups != null) { | ||
| 703 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 704 | } | ||
| 705 | } | ||
| 706 | for (int i = 0 ; i < ngroupsSnapshot ; i++) | ||
| 707 | suicide = groupsSnapshot[i].stopOrSuspend(suspend) || suicide; | ||
| 708 | |||
| 709 | return suicide; | ||
| 710 | } | ||
| 711 | |||
| 712 | /** | ||
| 713 | * Resumes all threads in this thread group. | ||
| 714 | * <p> | ||
| 715 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 716 | * called with no arguments; this may result in a security exception. | ||
| 717 | * <p> | ||
| 718 | * This method then calls the <code>resume</code> method on all the | ||
| 719 | * threads in this thread group and in all of its sub groups. | ||
| 720 | * | ||
| 721 | * @exception SecurityException if the current thread is not allowed to | ||
| 722 | * access this thread group or any of the threads in the | ||
| 723 | * thread group. | ||
| 724 | * @see java.lang.SecurityException | ||
| 725 | * @see java.lang.Thread#resume() | ||
| 726 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 727 | * @since JDK1.0 | ||
| 728 | * @deprecated This method is used solely in conjunction with | ||
| 729 | * <tt>Thread.suspend</tt> and <tt>ThreadGroup.suspend</tt>, | ||
| 730 | * both of which have been deprecated, as they are inherently | ||
| 731 | * deadlock-prone. See {@link Thread#suspend} for details. | ||
| 732 | */ | ||
| 733 | @Deprecated | ||
| 734 | public final void resume() { | ||
| 735 | int ngroupsSnapshot; | ||
| 736 | ThreadGroup[] groupsSnapshot; | ||
| 737 | synchronized (this) { | ||
| 738 | checkAccess(); | ||
| 739 | for (int i = 0 ; i < nthreads ; i++) { | ||
| 740 | threads[i].resume(); | ||
| 741 | } | ||
| 742 | ngroupsSnapshot = ngroups; | ||
| 743 | if (groups != null) { | ||
| 744 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 745 | } else { | ||
| 746 | groupsSnapshot = null; | ||
| 747 | } | ||
| 748 | } | ||
| 749 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 750 | groupsSnapshot[i].resume(); | ||
| 751 | } | ||
| 752 | } | ||
| 753 | |||
| 754 | /** | ||
| 755 | * Destroys this thread group and all of its subgroups. This thread | ||
| 756 | * group must be empty, indicating that all threads that had been in | ||
| 757 | * this thread group have since stopped. | ||
| 758 | * <p> | ||
| 759 | * First, the <code>checkAccess</code> method of this thread group is | ||
| 760 | * called with no arguments; this may result in a security exception. | ||
| 761 | * | ||
| 762 | * @exception IllegalThreadStateException if the thread group is not | ||
| 763 | * empty or if the thread group has already been destroyed. | ||
| 764 | * @exception SecurityException if the current thread cannot modify this | ||
| 765 | * thread group. | ||
| 766 | * @see java.lang.ThreadGroup#checkAccess() | ||
| 767 | * @since JDK1.0 | ||
| 768 | */ | ||
| 769 | public final void destroy() { | ||
| 770 | int ngroupsSnapshot; | ||
| 771 | ThreadGroup[] groupsSnapshot; | ||
| 772 | synchronized (this) { | ||
| 773 | checkAccess(); | ||
| 774 | if (destroyed || (nthreads > 0)) { | ||
| 775 | throw new IllegalThreadStateException(); | ||
| 776 | } | ||
| 777 | ngroupsSnapshot = ngroups; | ||
| 778 | if (groups != null) { | ||
| 779 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 780 | } else { | ||
| 781 | groupsSnapshot = null; | ||
| 782 | } | ||
| 783 | if (parent != null) { | ||
| 784 | destroyed = true; | ||
| 785 | ngroups = 0; | ||
| 786 | groups = null; | ||
| 787 | nthreads = 0; | ||
| 788 | threads = null; | ||
| 789 | } | ||
| 790 | } | ||
| 791 | for (int i = 0 ; i < ngroupsSnapshot ; i += 1) { | ||
| 792 | groupsSnapshot[i].destroy(); | ||
| 793 | } | ||
| 794 | if (parent != null) { | ||
| 795 | parent.remove(this); | ||
| 796 | } | ||
| 797 | } | ||
| 798 | |||
| 799 | /** | ||
| 800 | * Adds the specified Thread group to this group. | ||
| 801 | * @param g the specified Thread group to be added | ||
| 802 | * @exception IllegalThreadStateException If the Thread group has been destroyed. | ||
| 803 | */ | ||
| 804 | private final void add(ThreadGroup g){ | ||
| 805 | synchronized (this) { | ||
| 806 | if (destroyed) { | ||
| 807 | throw new IllegalThreadStateException(); | ||
| 808 | } | ||
| 809 | if (groups == null) { | ||
| 810 | groups = new ThreadGroup[4]; | ||
| 811 | } else if (ngroups == groups.length) { | ||
| 812 | groups = Arrays.copyOf(groups, ngroups * 2); | ||
| 813 | } | ||
| 814 | groups[ngroups] = g; | ||
| 815 | |||
| 816 | // This is done last so it doesn't matter in case the | ||
| 817 | // thread is killed | ||
| 818 | ngroups++; | ||
| 819 | } | ||
| 820 | } | ||
| 821 | |||
| 822 | /** | ||
| 823 | * Removes the specified Thread group from this group. | ||
| 824 | * @param g the Thread group to be removed | ||
| 825 | * @return if this Thread has already been destroyed. | ||
| 826 | */ | ||
| 827 | private void remove(ThreadGroup g) { | ||
| 828 | synchronized (this) { | ||
| 829 | if (destroyed) { | ||
| 830 | return; | ||
| 831 | } | ||
| 832 | for (int i = 0 ; i < ngroups ; i++) { | ||
| 833 | if (groups[i] == g) { | ||
| 834 | ngroups -= 1; | ||
| 835 | System.arraycopy(groups, i + 1, groups, i, ngroups - i); | ||
| 836 | // Zap dangling reference to the dead group so that | ||
| 837 | // the garbage collector will collect it. | ||
| 838 | groups[ngroups] = null; | ||
| 839 | break; | ||
| 840 | } | ||
| 841 | } | ||
| 842 | if (nthreads == 0) { | ||
| 843 | notifyAll(); | ||
| 844 | } | ||
| 845 | if (daemon && (nthreads == 0) && | ||
| 846 | (nUnstartedThreads == 0) && (ngroups == 0)) | ||
| 847 | { | ||
| 848 | destroy(); | ||
| 849 | } | ||
| 850 | } | ||
| 851 | } | ||
| 852 | |||
| 853 | |||
| 854 | /** | ||
| 855 | * Increments the count of unstarted threads in the thread group. | ||
| 856 | * Unstarted threads are not added to the thread group so that they | ||
| 857 | * can be collected if they are never started, but they must be | ||
| 858 | * counted so that daemon thread groups with unstarted threads in | ||
| 859 | * them are not destroyed. | ||
| 860 | */ | ||
| 861 | void addUnstarted() { | ||
| 862 | synchronized(this) { | ||
| 863 | if (destroyed) { | ||
| 864 | throw new IllegalThreadStateException(); | ||
| 865 | } | ||
| 866 | nUnstartedThreads++; | ||
| 867 | } | ||
| 868 | } | ||
| 869 | |||
| 870 | /** | ||
| 871 | * Adds the specified thread to this thread group. | ||
| 872 | * | ||
| 873 | * <p> Note: This method is called from both library code | ||
| 874 | * and the Virtual Machine. It is called from VM to add | ||
| 875 | * certain system threads to the system thread group. | ||
| 876 | * | ||
| 877 | * @param t | ||
| 878 | * the Thread to be added | ||
| 879 | * | ||
| 880 | * @throws IllegalThreadStateException | ||
| 881 | * if the Thread group has been destroyed | ||
| 882 | */ | ||
| 883 | void add(Thread t) { | ||
| 884 | synchronized (this) { | ||
| 885 | if (destroyed) { | ||
| 886 | throw new IllegalThreadStateException(); | ||
| 887 | } | ||
| 888 | if (threads == null) { | ||
| 889 | threads = new Thread[4]; | ||
| 890 | } else if (nthreads == threads.length) { | ||
| 891 | threads = Arrays.copyOf(threads, nthreads * 2); | ||
| 892 | } | ||
| 893 | threads[nthreads] = t; | ||
| 894 | |||
| 895 | // This is done last so it doesn't matter in case the | ||
| 896 | // thread is killed | ||
| 897 | nthreads++; | ||
| 898 | |||
| 899 | // The thread is now a fully fledged member of the group, even | ||
| 900 | // though it may, or may not, have been started yet. It will prevent | ||
| 901 | // the group from being destroyed so the unstarted Threads count is | ||
| 902 | // decremented. | ||
| 903 | nUnstartedThreads--; | ||
| 904 | } | ||
| 905 | } | ||
| 906 | |||
| 907 | /** | ||
| 908 | * Notifies the group that the thread {@code t} has failed | ||
| 909 | * an attempt to start. | ||
| 910 | * | ||
| 911 | * <p> The state of this thread group is rolled back as if the | ||
| 912 | * attempt to start the thread has never occurred. The thread is again | ||
| 913 | * considered an unstarted member of the thread group, and a subsequent | ||
| 914 | * attempt to start the thread is permitted. | ||
| 915 | * | ||
| 916 | * @param t | ||
| 917 | * the Thread whose start method was invoked | ||
| 918 | * | ||
| 919 | * @param failed | ||
| 920 | * true if the thread could not be started successfully | ||
| 921 | */ | ||
| 922 | void threadStartFailed(Thread t) { | ||
| 923 | synchronized(this) { | ||
| 924 | remove(t); | ||
| 925 | nUnstartedThreads++; | ||
| 926 | } | ||
| 927 | } | ||
| 928 | |||
| 929 | /** | ||
| 930 | * Notifies the group that the thread {@code t} has terminated. | ||
| 931 | * | ||
| 932 | * <p> Destroy the group if all of the following conditions are | ||
| 933 | * true: this is a daemon thread group; there are no more alive | ||
| 934 | * or unstarted threads in the group; there are no subgroups in | ||
| 935 | * this thread group. | ||
| 936 | * | ||
| 937 | * @param t | ||
| 938 | * the Thread that has terminated | ||
| 939 | */ | ||
| 940 | void threadTerminated(Thread t) { | ||
| 941 | synchronized (this) { | ||
| 942 | remove(t); | ||
| 943 | |||
| 944 | if (nthreads == 0) { | ||
| 945 | notifyAll(); | ||
| 946 | } | ||
| 947 | if (daemon && (nthreads == 0) && | ||
| 948 | (nUnstartedThreads == 0) && (ngroups == 0)) | ||
| 949 | { | ||
| 950 | destroy(); | ||
| 951 | } | ||
| 952 | } | ||
| 953 | } | ||
| 954 | |||
| 955 | /** | ||
| 956 | * Removes the specified Thread from this group. Invoking this method | ||
| 957 | * on a thread group that has been destroyed has no effect. | ||
| 958 | * | ||
| 959 | * @param t | ||
| 960 | * the Thread to be removed | ||
| 961 | */ | ||
| 962 | private void remove(Thread t) { | ||
| 963 | synchronized (this) { | ||
| 964 | if (destroyed) { | ||
| 965 | return; | ||
| 966 | } | ||
| 967 | for (int i = 0 ; i < nthreads ; i++) { | ||
| 968 | if (threads[i] == t) { | ||
| 969 | System.arraycopy(threads, i + 1, threads, i, --nthreads - i); | ||
| 970 | // Zap dangling reference to the dead thread so that | ||
| 971 | // the garbage collector will collect it. | ||
| 972 | threads[nthreads] = null; | ||
| 973 | break; | ||
| 974 | } | ||
| 975 | } | ||
| 976 | } | ||
| 977 | } | ||
| 978 | |||
| 979 | /** | ||
| 980 | * Prints information about this thread group to the standard | ||
| 981 | * output. This method is useful only for debugging. | ||
| 982 | * | ||
| 983 | * @since JDK1.0 | ||
| 984 | */ | ||
| 985 | public void list() { | ||
| 986 | list(System.out, 0); | ||
| 987 | } | ||
| 988 | void list(PrintStream out, int indent) { | ||
| 989 | int ngroupsSnapshot; | ||
| 990 | ThreadGroup[] groupsSnapshot; | ||
| 991 | synchronized (this) { | ||
| 992 | for (int j = 0 ; j < indent ; j++) { | ||
| 993 | out.print(" "); | ||
| 994 | } | ||
| 995 | out.println(this); | ||
| 996 | indent += 4; | ||
| 997 | for (int i = 0 ; i < nthreads ; i++) { | ||
| 998 | for (int j = 0 ; j < indent ; j++) { | ||
| 999 | out.print(" "); | ||
| 1000 | } | ||
| 1001 | out.println(threads[i]); | ||
| 1002 | } | ||
| 1003 | ngroupsSnapshot = ngroups; | ||
| 1004 | if (groups != null) { | ||
| 1005 | groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot); | ||
| 1006 | } else { | ||
| 1007 | groupsSnapshot = null; | ||
| 1008 | } | ||
| 1009 | } | ||
| 1010 | for (int i = 0 ; i < ngroupsSnapshot ; i++) { | ||
| 1011 | groupsSnapshot[i].list(out, indent); | ||
| 1012 | } | ||
| 1013 | } | ||
| 1014 | |||
| 1015 | /** | ||
| 1016 | * Called by the Java Virtual Machine when a thread in this | ||
| 1017 | * thread group stops because of an uncaught exception, and the thread | ||
| 1018 | * does not have a specific {@link Thread.UncaughtExceptionHandler} | ||
| 1019 | * installed. | ||
| 1020 | * <p> | ||
| 1021 | * The <code>uncaughtException</code> method of | ||
| 1022 | * <code>ThreadGroup</code> does the following: | ||
| 1023 | * <ul> | ||
| 1024 | * <li>If this thread group has a parent thread group, the | ||
| 1025 | * <code>uncaughtException</code> method of that parent is called | ||
| 1026 | * with the same two arguments. | ||
| 1027 | * <li>Otherwise, this method checks to see if there is a | ||
| 1028 | * {@linkplain Thread#getDefaultUncaughtExceptionHandler default | ||
| 1029 | * uncaught exception handler} installed, and if so, its | ||
| 1030 | * <code>uncaughtException</code> method is called with the same | ||
| 1031 | * two arguments. | ||
| 1032 | * <li>Otherwise, this method determines if the <code>Throwable</code> | ||
| 1033 | * argument is an instance of {@link ThreadDeath}. If so, nothing | ||
| 1034 | * special is done. Otherwise, a message containing the | ||
| 1035 | * thread's name, as returned from the thread's {@link | ||
| 1036 | * Thread#getName getName} method, and a stack backtrace, | ||
| 1037 | * using the <code>Throwable</code>'s {@link | ||
| 1038 | * Throwable#printStackTrace printStackTrace} method, is | ||
| 1039 | * printed to the {@linkplain System#err standard error stream}. | ||
| 1040 | * </ul> | ||
| 1041 | * <p> | ||
| 1042 | * Applications can override this method in subclasses of | ||
| 1043 | * <code>ThreadGroup</code> to provide alternative handling of | ||
| 1044 | * uncaught exceptions. | ||
| 1045 | * | ||
| 1046 | * @param t the thread that is about to exit. | ||
| 1047 | * @param e the uncaught exception. | ||
| 1048 | * @since JDK1.0 | ||
| 1049 | */ | ||
| 1050 | public void uncaughtException(Thread t, Throwable e) { | ||
| 1051 | if (parent != null) { | ||
| 1052 | parent.uncaughtException(t, e); | ||
| 1053 | } else { | ||
| 1054 | Thread.UncaughtExceptionHandler ueh = | ||
| 1055 | Thread.getDefaultUncaughtExceptionHandler(); | ||
| 1056 | if (ueh != null) { | ||
| 1057 | ueh.uncaughtException(t, e); | ||
| 1058 | } else if (!(e instanceof ThreadDeath)) { | ||
| 1059 | System.err.print("Exception in thread \"" | ||
| 1060 | + t.getName() + "\" "); | ||
| 1061 | e.printStackTrace(System.err); | ||
| 1062 | } | ||
| 1063 | } | ||
| 1064 | } | ||
| 1065 | |||
| 1066 | /** | ||
| 1067 | * Used by VM to control lowmem implicit suspension. | ||
| 1068 | * | ||
| 1069 | * @param b boolean to allow or disallow suspension | ||
| 1070 | * @return true on success | ||
| 1071 | * @since JDK1.1 | ||
| 1072 | * @deprecated The definition of this call depends on {@link #suspend}, | ||
| 1073 | * which is deprecated. Further, the behavior of this call | ||
| 1074 | * was never specified. | ||
| 1075 | */ | ||
| 1076 | @Deprecated | ||
| 1077 | public boolean allowThreadSuspension(boolean b) { | ||
| 1078 | this.vmAllowSuspension = b; | ||
| 1079 | if (!b) { | ||
| 1080 | VM.unsuspendSomeThreads(); | ||
| 1081 | } | ||
| 1082 | return true; | ||
| 1083 | } | ||
| 1084 | |||
| 1085 | /** | ||
| 1086 | * Returns a string representation of this Thread group. | ||
| 1087 | * | ||
| 1088 | * @return a string representation of this thread group. | ||
| 1089 | * @since JDK1.0 | ||
| 1090 | */ | ||
| 1091 | public String toString() { | ||
| 1092 | return getClass().getName() + "[name=" + getName() + ",maxpri=" + maxPriority + "]"; | ||
| 1093 | } | ||
| 1094 | } | ||