src/os/aix/vm/os_aix.cpp
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src/os/aix/vm/os_aix.cpp

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*** 2655,2669 **** void os::hint_no_preempt() {} //////////////////////////////////////////////////////////////////////////////// // suspend/resume support ! // the low-level signal-based suspend/resume support is a remnant from the // old VM-suspension that used to be for java-suspension, safepoints etc, ! // within hotspot. Now there is a single use-case for this: ! // - calling get_thread_pc() on the VMThread by the flat-profiler task ! // that runs in the watcher thread. // The remaining code is greatly simplified from the more general suspension // code that used to be used. // // The protocol is quite simple: // - suspend: --- 2655,2668 ---- void os::hint_no_preempt() {} //////////////////////////////////////////////////////////////////////////////// // suspend/resume support ! // The low-level signal-based suspend/resume support is a remnant from the // old VM-suspension that used to be for java-suspension, safepoints etc, ! // within hotspot. Currently used by JFR's OSThreadSampler ! // // The remaining code is greatly simplified from the more general suspension // code that used to be used. // // The protocol is quite simple: // - suspend:
*** 2675,2685 **** --- 2674,2690 ---- // - sets target osthread state to continue // - sends signal to end the sigsuspend loop in the SR_handler // // Note that the SR_lock plays no role in this suspend/resume protocol, // but is checked for NULL in SR_handler as a thread termination indicator. + // The SR_lock is, however, used by JavaThread::java_suspend()/java_resume() APIs. // + // Note that resume_clear_context() and suspend_save_context() are needed + // by SR_handler(), so that fetch_frame_from_ucontext() works, + // which in part is used by: + // - Forte Analyzer: AsyncGetCallTrace() + // - StackBanging: get_frame_at_stack_banging_point() static void resume_clear_context(OSThread *osthread) { osthread->set_ucontext(NULL); osthread->set_siginfo(NULL); }
*** 3682,3729 **** do_task(context); do_resume(_thread->osthread()); } } - class PcFetcher : public os::SuspendedThreadTask { - public: - PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {} - ExtendedPC result(); - protected: - void do_task(const os::SuspendedThreadTaskContext& context); - private: - ExtendedPC _epc; - }; - - ExtendedPC PcFetcher::result() { - guarantee(is_done(), "task is not done yet."); - return _epc; - } - - void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) { - Thread* thread = context.thread(); - OSThread* osthread = thread->osthread(); - if (osthread->ucontext() != NULL) { - _epc = os::Aix::ucontext_get_pc((const ucontext_t *) context.ucontext()); - } else { - // NULL context is unexpected, double-check this is the VMThread. - guarantee(thread->is_VM_thread(), "can only be called for VMThread"); - } - } - - // Suspends the target using the signal mechanism and then grabs the PC before - // resuming the target. Used by the flat-profiler only - ExtendedPC os::get_thread_pc(Thread* thread) { - // Make sure that it is called by the watcher for the VMThread. - assert(Thread::current()->is_Watcher_thread(), "Must be watcher"); - assert(thread->is_VM_thread(), "Can only be called for VMThread"); - - PcFetcher fetcher(thread); - fetcher.run(); - return fetcher.result(); - } - //////////////////////////////////////////////////////////////////////////////// // debug support bool os::find(address addr, outputStream* st) { --- 3687,3696 ----
src/os/aix/vm/os_aix.cpp
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