Chris contact me offline if you want this is exactly what http://privateeye.io does. I can get a build over to you.
On Fri, May 27, 2016 at 8:04 PM, Chris Swiedler <cswied...@trionworlds.com> wrote: > Thanks. I’ll try to use the profiler, but this problem doesn’t happen at > startup, and running the application under profiling for eight hours is > probably infeasible. > > > > I see that at one point mono support signal-based enabling/disabling of the > profiler, like how SIGUSR2 toggles the trace mechanism on and off. Is that > sort of functionality ever going to be re-added? Currently there’s the > heapshot option via the TCP listener, perhaps there could be enable/disable > commands via that mechanism? > > > > chris > > > > From: Ludovic Henry [mailto:ludo...@xamarin.com] > Sent: Friday, May 27, 2016 1:27 AM > > > To: Chris Swiedler <cswied...@trionworlds.com>; mono-devel-list > <mono-devel-list@lists.ximian.com> > Subject: Re: [Mono-dev] High threadpool CPU usage > > > > Hi Chris, > > > > The signal handler you are seeing is the GC signalling every thread to > suspend them. So yes you are right, that's the sgen collector stopping the > world. > > > > To track down the large number of allocation, I would encourage you to try > the log profiler (documentation: > http://www.mono-project.com/docs/debug+profile/profile/profiler/ ). That > should give you some more insights in where the allocations are coming from. > > > > Thank you, > > Ludovic > > > > On Thu, May 26, 2016 at 8:20 PM Chris Swiedler <cswied...@trionworlds.com> > wrote: > > Thanks, Ludovic. I’m using mono-4.2.3. The ‘massive amounts of GC’ idea > makes sense based on what I’m seeing. When I run pstack, I get a number of > threadpool threads in stacks with: > > > > #0 0x00007fdff1c6a952 in do_sigsuspend (set=0x954220 <suspend_signal_mask>) > at ../sysdeps/unix/sysv/linux/sigsuspend.c:32 > > #1 __GI___sigsuspend (set=set@entry=0x954220 <suspend_signal_mask>) at > ../sysdeps/unix/sysv/linux/sigsuspend.c:46 > > #2 0x00000000005c7534 in suspend_thread (info=0x7fdf480008c0, > context=context@entry=0x7fde997ea1c0) at sgen-os-posix.c:126 > > #3 0x00000000005c771f in suspend_handler (_dummy=<optimized out>, > _info=<optimized out>, context=0x7fde997ea1c0) at sgen-os-posix.c:153 > > #4 <signal handler called> > > > > I thought this was related to GDB / pstack attaching, but it’s actually the > suspend handling for the sgen collector, right? > > > > Is a thread suspending itself CPU-intensive? I see lots of threads with high > CPU at any point, which seems to indicate that this wouldn’t just be the CPU > usage of the collector thread itself. > > > > Do you have any suggestions for how to track down the large numbers of > allocations? This isn’t very easy to reproduce, but now that I know what to > look for, I might be able to get it to happen in a test environment. > > > > chris > > > > From: Ludovic Henry [mailto:ludo...@xamarin.com] > Sent: Thursday, May 26, 2016 8:43 AM > To: Chris Swiedler <cswied...@trionworlds.com>; mono-devel-list > <mono-devel-list@lists.ximian.com> > Subject: Re: [Mono-dev] High threadpool CPU usage > > > > Hi Chris, > > > > The first stacktrace you are observing is for threadpool thread parking. We > use this technique for threads that are currently not doing anything, to > keep them around for a little while (5-60 seconds) so if we have burst of > usage, we do not end up destroying and creating threads all the time. > > > > The second stacktrace you are observing is, as you noted, when performing a > garbage collection, when the GC thread is suspending all the running > threads. So if you are witnessing this trace very often, it means a thread > is allocating memory very quickly triggering GC collection very often. > > > > So I would need more information to tell you exactly why it would use 100% > CPU. Also which version of Mono are you running? > > > > Thank you very much, > > Ludovic > > On Wed, May 25, 2016 at 8:30 PM Chris Swiedler <cswied...@trionworlds.com> > wrote: > > We have a server app which is periodically going into a mode where all > threadpool threads start running at very high CPU. I've run pstack when it's > in this mode, and every time I do it, nearly all the threadpool threads have > this stack: > > #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at > ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238 > #1 0x0000000000618817 in mono_cond_timedwait_ms > (cond=cond@entry=0x7fe7ee1fddc0, mutex=0x241eb78, timeout_ms=<optimized > out>) at mono-mutex.c:181 > #2 0x0000000000586f28 in worker_park () at threadpool-ms.c:509 > #3 worker_thread (data=<optimized out>) at threadpool-ms.c:607 > #4 0x00000000005841e9 in start_wrapper_internal (data=<optimized out>) at > threads.c:725 > #5 start_wrapper (data=<optimized out>) at threads.c:772 > #6 0x0000000000621026 in inner_start_thread (arg=0x7fe831df4650) at > mono-threads-posix.c:97 > #7 0x00007fe88a55edf5 in start_thread (arg=0x7fe7ee1fe700) at > pthread_create.c:308 > #8 0x00007fe88a28c1ad in clone () at > ../sysdeps/unix/sysv/linux/x86_64/clone.S:113 > > Usually one thread will have a stack like this: > > #0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85 > #1 0x000000000061aa37 in mono_sem_wait (sem=0x9542c0 > <suspend_ack_semaphore>, alertable=alertable@entry=0) at > mono-semaphore.c:107 > #2 0x00000000005c77bd in sgen_wait_for_suspend_ack (count=count@entry=18) > at sgen-os-posix.c:188 > #3 0x00000000005c78f9 in sgen_thread_handshake (suspend=suspend@entry=1) at > sgen-os-posix.c:224 > #4 0x00000000005c7e92 in sgen_client_stop_world > (generation=generation@entry=0) at sgen-stw.c:234 > #5 0x00000000005e6aca in sgen_stop_world (generation=0) at sgen-gc.c:3389 > #6 0x00000000005e6c29 in sgen_perform_collection (requested_size=4096, > generation_to_collect=0, reason=0x6d9595 "Nursery full", wait_to_finish=0) > at sgen-gc.c:2322#7 0x00000000005da62a in sgen_alloc_obj_nolock > (vtable=vtable@entry=0x7fe85c0343c0, size=size@entry=128) at > sgen-alloc.c:291 > #8 0x00000000005da913 in sgen_alloc_obj > (vtable=vtable@entry=0x7fe85c0343c0, size=128) at sgen-alloc.c:457 > #9 0x00000000005c86e9 in mono_gc_alloc_obj > (vtable=vtable@entry=0x7fe85c0343c0, size=<optimized out>) at > sgen-mono.c:936 > #10 0x00000000005a8b54 in mono_object_new_alloc_specific > (vtable=vtable@entry=0x7fe85c0343c0) at object.c:4385 > #11 0x00000000005a8bf0 in mono_object_new_specific (vtable=0x7fe85c0343c0) > at object.c:4379 > #12 0x00000000005a8c8c in mono_object_new (domain=domain@entry=0x1ded1c0, > klass=<optimized out>) at object.c:4318 > #13 0x00000000005ac1c9 in mono_async_result_new > (domain=domain@entry=0x1ded1c0, handle=handle@entry=0x0, state=0x0, > data=data@entry=0x0, object_data=object_data@entry=0x7fe8838af020) at > object.c:5768 > #14 0x00000000005887ff in mono_threadpool_ms_begin_invoke (domain=0x1ded1c0, > target=target@entry=0x7fe8838aee38, method=method@entry=0x2963d28, > params=params@entry=0x7fe7ed9f8f10) at threadpool-ms.c:1300 > #15 0x000000000054b547 in mono_delegate_begin_invoke > (delegate=0x7fe8838aee38, params=0x7fe7ed9f8f10) at marshal.c:2111 > #16 0x00000000416d29d8 in ?? () > #17 0x0000000000000000 in ?? () > > Just from reading the first stack, it doesn't look like > mono_cond_timedwait_ms would spin, at least as long as the timeout_ms wasn't > 0. For the second stack, I don't know whether that's a normal garbage > collection pass or (since we see it frequently) a sign that garbage > collection is happening too often. > > Can anyone give me some pointers for where to dig more deeply? > > Thanks, > chris > _______________________________________________ > Mono-devel-list mailing list > Mono-devel-list@lists.ximian.com > http://lists.ximian.com/mailman/listinfo/mono-devel-list > > > _______________________________________________ > Mono-devel-list mailing list > Mono-devel-list@lists.ximian.com > http://lists.ximian.com/mailman/listinfo/mono-devel-list > -- Studying for the Turing test _______________________________________________ Mono-devel-list mailing list Mono-devel-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-devel-list
