From 2a0687c8905d9f9d1c8d4e1dee255a8ceabba5e5 Mon Sep 17 00:00:00 2001 From: David Srbecky Date: Wed, 24 Feb 2021 15:52:50 +0000 Subject: Revert "Remove support for stuck threads" Revert submission 1601635 Reason for revert: b/181123058 Reverted Changes: I8f5cd1266:Remove support for stuck threads Ifdb59336d:Remove DisableOnDebug (new in 4.12) as it is not s... I6abae5aed:Extra generic type information to aid certain java... I5ec909df6:Upgrade external/junit to 4.13.2 Change-Id: Icf0a7b88b0004e60cd4139cb10be62af5bdc68d2 --- .../internal/runners/statements/FailOnTimeout.java | 155 ++++++++++++++++++++- src/main/java/org/junit/rules/Timeout.java | 33 +++++ 2 files changed, 186 insertions(+), 2 deletions(-) (limited to 'src/main/java') diff --git a/src/main/java/org/junit/internal/runners/statements/FailOnTimeout.java b/src/main/java/org/junit/internal/runners/statements/FailOnTimeout.java index 9fad35b..9362cc1 100644 --- a/src/main/java/org/junit/internal/runners/statements/FailOnTimeout.java +++ b/src/main/java/org/junit/internal/runners/statements/FailOnTimeout.java @@ -1,5 +1,8 @@ package org.junit.internal.runners.statements; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; import java.util.concurrent.Callable; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutionException; @@ -7,6 +10,9 @@ import java.util.concurrent.FutureTask; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; +import org.junit.internal.management.ManagementFactory; +import org.junit.internal.management.ThreadMXBean; +import org.junit.runners.model.MultipleFailureException; import org.junit.runners.model.Statement; import org.junit.runners.model.TestTimedOutException; @@ -14,6 +20,7 @@ public class FailOnTimeout extends Statement { private final Statement originalStatement; private final TimeUnit timeUnit; private final long timeout; + private final boolean lookForStuckThread; /** * Returns a new builder for building an instance. @@ -40,6 +47,7 @@ public class FailOnTimeout extends Statement { originalStatement = statement; timeout = builder.timeout; timeUnit = builder.unit; + lookForStuckThread = builder.lookForStuckThread; } /** @@ -48,6 +56,7 @@ public class FailOnTimeout extends Statement { * @since 4.12 */ public static class Builder { + private boolean lookForStuckThread = false; private long timeout = 0; private TimeUnit unit = TimeUnit.SECONDS; @@ -79,6 +88,20 @@ public class FailOnTimeout extends Statement { return this; } + /** + * Specifies whether to look for a stuck thread. If a timeout occurs and this + * feature is enabled, the test will look for a thread that appears to be stuck + * and dump its backtrace. This feature is experimental. Behavior may change + * after the 4.12 release in response to feedback. + * + * @param enable {@code true} to enable the feature + * @return {@code this} for method chaining. + */ + public Builder withLookingForStuckThread(boolean enable) { + this.lookForStuckThread = enable; + return this; + } + /** * Builds a {@link FailOnTimeout} instance using the values in this builder, * wrapping the given statement. @@ -97,7 +120,8 @@ public class FailOnTimeout extends Statement { public void evaluate() throws Throwable { CallableStatement callable = new CallableStatement(); FutureTask task = new FutureTask(callable); - Thread thread = new Thread(task, "Time-limited test"); + ThreadGroup threadGroup = threadGroupForNewThread(); + Thread thread = new Thread(threadGroup, task, "Time-limited test"); thread.setDaemon(true); thread.start(); callable.awaitStarted(); @@ -107,6 +131,31 @@ public class FailOnTimeout extends Statement { } } + private ThreadGroup threadGroupForNewThread() { + if (!lookForStuckThread) { + // Use the default ThreadGroup (usually the one from the current + // thread). + return null; + } + + // Create the thread in a new ThreadGroup, so if the time-limited thread + // becomes stuck, getStuckThread() can find the thread likely to be the + // culprit. + ThreadGroup threadGroup = new ThreadGroup("FailOnTimeoutGroup"); + if (!threadGroup.isDaemon()) { + // Mark the new ThreadGroup as a daemon thread group, so it will be + // destroyed after the time-limited thread completes. By ensuring the + // ThreadGroup is destroyed, any data associated with the ThreadGroup + // (ex: via java.beans.ThreadGroupContext) is destroyed. + try { + threadGroup.setDaemon(true); + } catch (SecurityException e) { + // Swallow the exception to keep the same behavior as in JUnit 4.12. + } + } + return threadGroup; + } + /** * Wait for the test task, returning the exception thrown by the test if the * test failed, an exception indicating a timeout if the test timed out, or @@ -131,12 +180,114 @@ public class FailOnTimeout extends Statement { private Exception createTimeoutException(Thread thread) { StackTraceElement[] stackTrace = thread.getStackTrace(); + final Thread stuckThread = lookForStuckThread ? getStuckThread(thread) : null; Exception currThreadException = new TestTimedOutException(timeout, timeUnit); if (stackTrace != null) { currThreadException.setStackTrace(stackTrace); thread.interrupt(); } - return currThreadException; + if (stuckThread != null) { + Exception stuckThreadException = + new Exception("Appears to be stuck in thread " + + stuckThread.getName()); + stuckThreadException.setStackTrace(getStackTrace(stuckThread)); + return new MultipleFailureException( + Arrays.asList(currThreadException, stuckThreadException)); + } else { + return currThreadException; + } + } + + /** + * Retrieves the stack trace for a given thread. + * @param thread The thread whose stack is to be retrieved. + * @return The stack trace; returns a zero-length array if the thread has + * terminated or the stack cannot be retrieved for some other reason. + */ + private StackTraceElement[] getStackTrace(Thread thread) { + try { + return thread.getStackTrace(); + } catch (SecurityException e) { + return new StackTraceElement[0]; + } + } + + /** + * Determines whether the test appears to be stuck in some thread other than + * the "main thread" (the one created to run the test). This feature is experimental. + * Behavior may change after the 4.12 release in response to feedback. + * @param mainThread The main thread created by {@code evaluate()} + * @return The thread which appears to be causing the problem, if different from + * {@code mainThread}, or {@code null} if the main thread appears to be the + * problem or if the thread cannot be determined. The return value is never equal + * to {@code mainThread}. + */ + private Thread getStuckThread(Thread mainThread) { + List threadsInGroup = getThreadsInGroup(mainThread.getThreadGroup()); + if (threadsInGroup.isEmpty()) { + return null; + } + + // Now that we have all the threads in the test's thread group: Assume that + // any thread we're "stuck" in is RUNNABLE. Look for all RUNNABLE threads. + // If just one, we return that (unless it equals threadMain). If there's more + // than one, pick the one that's using the most CPU time, if this feature is + // supported. + Thread stuckThread = null; + long maxCpuTime = 0; + for (Thread thread : threadsInGroup) { + if (thread.getState() == Thread.State.RUNNABLE) { + long threadCpuTime = cpuTime(thread); + if (stuckThread == null || threadCpuTime > maxCpuTime) { + stuckThread = thread; + maxCpuTime = threadCpuTime; + } + } + } + return (stuckThread == mainThread) ? null : stuckThread; + } + + /** + * Returns all active threads belonging to a thread group. + * @param group The thread group. + * @return The active threads in the thread group. The result should be a + * complete list of the active threads at some point in time. Returns an empty list + * if this cannot be determined, e.g. because new threads are being created at an + * extremely fast rate. + */ + private List getThreadsInGroup(ThreadGroup group) { + final int activeThreadCount = group.activeCount(); // this is just an estimate + int threadArraySize = Math.max(activeThreadCount * 2, 100); + for (int loopCount = 0; loopCount < 5; loopCount++) { + Thread[] threads = new Thread[threadArraySize]; + int enumCount = group.enumerate(threads); + if (enumCount < threadArraySize) { + return Arrays.asList(threads).subList(0, enumCount); + } + // if there are too many threads to fit into the array, enumerate's result + // is >= the array's length; therefore we can't trust that it returned all + // the threads. Try again. + threadArraySize += 100; + } + // threads are proliferating too fast for us. Bail before we get into + // trouble. + return Collections.emptyList(); + } + + /** + * Returns the CPU time used by a thread, if possible. + * @param thr The thread to query. + * @return The CPU time used by {@code thr}, or 0 if it cannot be determined. + */ + private long cpuTime(Thread thr) { + ThreadMXBean mxBean = ManagementFactory.getThreadMXBean(); + if (mxBean.isThreadCpuTimeSupported()) { + try { + return mxBean.getThreadCpuTime(thr.getId()); + } catch (UnsupportedOperationException e) { + } + } + return 0; } private class CallableStatement implements Callable { diff --git a/src/main/java/org/junit/rules/Timeout.java b/src/main/java/org/junit/rules/Timeout.java index 5cf905a..334a923 100644 --- a/src/main/java/org/junit/rules/Timeout.java +++ b/src/main/java/org/junit/rules/Timeout.java @@ -40,6 +40,7 @@ import java.util.concurrent.TimeUnit; public class Timeout implements TestRule { private final long timeout; private final TimeUnit timeUnit; + private final boolean lookForStuckThread; /** * Returns a new builder for building an instance. @@ -79,6 +80,7 @@ public class Timeout implements TestRule { public Timeout(long timeout, TimeUnit timeUnit) { this.timeout = timeout; this.timeUnit = timeUnit; + lookForStuckThread = false; } /** @@ -90,6 +92,7 @@ public class Timeout implements TestRule { protected Timeout(Builder builder) { timeout = builder.getTimeout(); timeUnit = builder.getTimeUnit(); + lookForStuckThread = builder.getLookingForStuckThread(); } /** @@ -121,6 +124,16 @@ public class Timeout implements TestRule { return unit.convert(timeout, timeUnit); } + /** + * Gets whether this {@code Timeout} will look for a stuck thread + * when the test times out. + * + * @since 4.12 + */ + protected final boolean getLookingForStuckThread() { + return lookForStuckThread; + } + /** * Creates a {@link Statement} that will run the given * {@code statement}, and timeout the operation based @@ -133,6 +146,7 @@ public class Timeout implements TestRule { Statement statement) throws Exception { return FailOnTimeout.builder() .withTimeout(timeout, timeUnit) + .withLookingForStuckThread(lookForStuckThread) .build(statement); } @@ -190,6 +204,25 @@ public class Timeout implements TestRule { return timeUnit; } + /** + * Specifies whether to look for a stuck thread. If a timeout occurs and this + * feature is enabled, the rule will look for a thread that appears to be stuck + * and dump its backtrace. This feature is experimental. Behavior may change + * after the 4.12 release in response to feedback. + * + * @param enable {@code true} to enable the feature + * @return {@code this} for method chaining. + */ + public Builder withLookingForStuckThread(boolean enable) { + this.lookForStuckThread = enable; + return this; + } + + protected boolean getLookingForStuckThread() { + return lookForStuckThread; + } + + /** * Builds a {@link Timeout} instance using the values in this builder., */ -- cgit v1.2.3