thread1.callAndAssertReturns(enter());
    thread2.callAndAssertBlocks(enter());
    thread1.callAndAssertReturns(leave());
    thread2.assertPriorCallReturns(enter());
  }

  public final void testTryEnter() throws Exception {
    thread1.callAndAssertReturns(true, tryEnter());
    thread2.callAndAssertReturns(false, tryEnter());
    thread1.callAndAssertReturns(true, tryEnter());

    thread1.callAndAssertReturns(enter());
    thread2.callAndAssertBlocks(enter());
    thread1.callAndAssertReturns(leave());
    thread2.assertPriorCallReturns(enter());
  }

  public final void testTryEnter() throws Exception {
    thread1.callAndAssertReturns(true, tryEnter());
    thread2.callAndAssertReturns(false, tryEnter());
    thread1.callAndAssertReturns(true, tryEnter());

                    thread.block()
                    instant.thread1
                }
            }
            workerThread {
                thread.blockUntil.start
                state.applyToMutableState {
                    instant.thread2
                }
            }
        }

        then:
        instant.thread2 > instant.thread1
    }

        Map<Thread, Throwable> exceptions = [:]
        def exceptionHandler = { thread, exception ->
            exceptions.put(thread, exception)
            exception.printStackTrace()
        } as Thread.UncaughtExceptionHandler

        when:
        def thread1 = new Thread({
            println "Work 1 started"
            step.execute(work, context)

package main

/*
#include <stdint.h>
#include <stdlib.h>
#include <signal.h>
#include <pthread.h>

volatile int32_t spinlock;

// Note that this thread is only started if GO_START_SIGPROF_THREAD
// is set in the environment, which is only done when running the
// CgoExternalThreadSIGPROF test.
static void *thread1(void *p) {
	(void)p;
	while (spinlock == 0)
		;
	pthread_kill(pthread_self(), SIGPROF);

            start {
                workerLeaseService.withLocks([projectLock]) {
                    instant.thread1
                    thread.blockUntil.thread2
                    sleep 100
                }
            }
            start {
                thread.blockUntil.thread1
                instant.thread2
                workerLeaseService.withLocks([projectLock]) {
                    thread2Executed = true

		die("sigaction");
	}
}

// Test raising SIGIO on a C thread with an alternate signal stack
// when there is a Go signal handler for SIGIO.
static void* thread1(void* arg __attribute__ ((unused))) {
	stack_t ss;
	int i;
	stack_t nss;
	struct timespec ts;

	// Set up an alternate signal stack for this thread.
	memset(&ss, 0, sizeof ss);
	ss.ss_sp = malloc(CSIGSTKSZ);
	if (ss.ss_sp == NULL) {

     * there's another race: If the first thread fails with an exception and a second thread
     * immediately fails with the same exception:
     *
     * Thread1: calls setException(), which returns true, context switch before it can CAS
     * seenExceptions to its exception
     *
     * Thread2: calls setException(), which returns false, CASes seenExceptions to its exception,

     * there's another race: If the first thread fails with an exception and a second thread
     * immediately fails with the same exception:
     *
     * Thread1: calls setException(), which returns true, context switch before it can CAS
     * seenExceptions to its exception
     *
     * Thread2: calls setException(), which returns false, CASes seenExceptions to its exception,

 * example involving two locks and two threads, deadlock occurs when one thread acquires Lock A, and
 * then Lock B, while another thread acquires Lock B, and then Lock A:
 *
 * <pre>
 * Thread1: acquire(LockA) --X acquire(LockB)
 * Thread2: acquire(LockB) --X acquire(LockA)
 * </pre>
 *
 * <p>Neither thread will progress because each is waiting for the other. In more complex