Name: dd4877 Date: 10/12/2001


daniel.daugherty@Sun 2001-10-12

While working on the following bug:

4510838 3/2 self-suspend race with GetCallTrace

I ran into a case where both the _external_suspend and _internal_suspend
fields were set but no internal suspension was taking place. The VMThread
was not doing a safepoint, we were not shutting down the VM, and the flat
profiler was not running.

There is a problem with the flag resetting logic during a resume:

        if (java_thread->is_external_suspend()) {
          // external request can only clear pending external suspend
          if (ext_req) {
            java_thread->clear_external_suspend();
            return 0;
          }
        } else if (java_thread->is_internal_suspend()) {
          // internal request can only clear pending internal suspend
          if (!ext_req) {
            java_thread->clear_internal_suspend();
            return 0;
          }
        }

when both _external_suspend and _internal_suspend are true, the
_internal_suspend flag will never get cleared by this logic.

I believe this logic problem appears in two places in thread.cpp.

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