daniel.daugherty@Eng 2001-02-09

This bug was encountered while chasing the following bug:

4369489 2/5 jdb does not work on Linux platform.

This bug is the second layer of that onion.

I have a test case that exercises JVM/DI raw monitors and thread
suspend/resume. This test case passes 6000 loops (3 worker threads in
each loop for 1 minute of execution time on an Ultra 30) with the
current service_baseline on Solaris SPARC, Solaris X86 and Win32.

However, on RedHat 6.2 Linux, the test case hangs on the *first*
iteration.

Here is a transaction diagram of the test:

//
// main blocker contender resumer
// ================= ================ =================== ================
// launch blocker
// <launch returns> blocker running
// launch contender enter threadLock
// <launch returns> wait for notify contender running
// launch resumer : block on threadLock
// <launch returns> : : resumer running
// suspend contender : <suspended> wait for notify
// <ready to test> : : :
// : : : :
// notify blocker exit threadLock : :
// join blocker : : enter threadLock*
// <join returns> blocker exits <resumed> resume contender
// join resumer : exit threadLock
// <join returns> enter threadLock resumer exits
// join contender exit threadLock
// <join returns> contender exits
//

On Linux, the resumer thread fails to enter threadLock even though
there is no owner. The blocker thread has exited threadLock and the
contender thread is suspended.

I have added a test case that exercises JVM/PI raw monitors and thread
suspend/resume. Initially this test case failed on all four platforms.
But after discussing this with Karen, I changed JVM/PI SuspendThread()
to immediately suspend threads in state _thread_in_native. With that
fix in place, this test case passes 1900 loops (3 worker threads in
each loop for 1 minute of execution time on an Ultra 30) with the
current service_baseline on Solaris SPARC, Solaris X86 and Win32.

However, on RedHat 6.2 Linux, the JVM/PI test case also hangs on the
first iteration.

I have added a test case that exercises Java ObjectMonitors and JVM/DI
thread suspend/resume. Like in 4333847, this test shows that it is
necessary for JVM/DI SuspendThread() calls to not allow pending
ObjectMonitor.enter() calls to complete. This test case fails on all
four platforms.

I have added a test case that exercises Java ObjectMonitors and JVM/PI
thread suspend/resume. Like in 4333847, this test shows that it is
necessary for JVM/PI SuspendThread() calls to not allow pending
ObjectMonitor.enter() calls to complete. This test case fails on all
four platforms.

daniel.daugherty@Eng 2001-03-23

Just for completeness, I have added a test case that exercises Java
ObjectMonitors and Thread.suspend() and Thread.resume(). I realize
that Thread.suspend() and Thread.resume() are deprecated, but we need
to make sure that bad things don't happen.