runtime/pprof: hangs when using pprof on a CPU-intensive program on OS X #5519
Description
by akalin:
What steps will reproduce the problem? If possible, include a link to a program on play.golang.org. 1. Download aks_debug.go from http://play.golang.org/p/SUNgPMcfIM or https://github.com/akalin/aks-go/blob/debug/aks_debug.go 2. build (tested with go 1.1): go build aks_debug.go 3. the most reliable way to repro would be to run: for i in $(seq 1 300); do (env GOGCTRACE=1 ./aks_debug >&/tmp/aks_debug.$i &); done You'd expect all programs to terminate, but chances are, when your computer settles down, there will be one or two aks_debug processes still hanging around. Check with ps. For example: PID TTY TIME CMD 23780 ttys000 0:00.01 -bash 23826 ttys000 0:00.00 tmux att 26765 ttys001 0:02.11 -bash 27792 ttys001 0:02.04 ./aks_debug 27904 ttys001 0:02.09 ./aks_debug 17273 ttys002 0:00.04 -bash 6770 ttys003 0:00.83 -bash Check which output files correspond to those processes: $ lsof /tmp/aks_debug.* COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME aks_debug 27792 akalin 1w REG 1,4 2404 9553026 /private/tmp/aks_debug.5 aks_debug 27792 akalin 2w REG 1,4 2404 9553026 /private/tmp/aks_debug.5 aks_debug 27904 akalin 1w REG 1,4 2404 9553082 /private/tmp/aks_debug.61 aks_debug 27904 akalin 2w REG 1,4 2404 9553082 /private/tmp/aks_debug.61 Then send a SIGQUIT to one of those to get the output: kill -s SIGQUIT 27792 less /tmp/aks_debug.5 For example, I get the below log output. Looks like it's stuck on a write syscall for the pprof output? Let me know if I can do anything more. -- START aks_debug.5 -- gc1(1): 0+0+0 ms, 0 -> 0 MB 20 -> 22 (23-1) objects, 0(0) handoff, 0(0) steal, 0 /0/0 yields 2013/05/14 02:33:47 0: multiplying... 2013/05/14 02:33:47 0: multiplying done; shifting... 2013/05/14 02:33:47 0: not shifting 2013/05/14 02:33:47 1: multiplying... 2013/05/14 02:33:47 1: multiplying done; shifting... 2013/05/14 02:33:47 1: not shifting 2013/05/14 02:33:47 2: multiplying... 2013/05/14 02:33:47 2: multiplying done; shifting... 2013/05/14 02:33:47 2: not shifting 2013/05/14 02:33:47 3: multiplying... 2013/05/14 02:33:47 3: multiplying done; shifting... 2013/05/14 02:33:47 3: not shifting 2013/05/14 02:33:47 4: multiplying... 2013/05/14 02:33:47 4: multiplying done; shifting... 2013/05/14 02:33:47 4: not shifting 2013/05/14 02:33:47 5: multiplying... 2013/05/14 02:33:47 5: multiplying done; shifting... 2013/05/14 02:33:47 5: not shifting 2013/05/14 02:33:47 6: multiplying... 2013/05/14 02:33:47 6: multiplying done; shifting... 2013/05/14 02:33:47 6: not shifting 2013/05/14 02:33:47 7: multiplying... 2013/05/14 02:33:47 7: multiplying done; shifting... 2013/05/14 02:33:47 7: not shifting 2013/05/14 02:33:47 8: multiplying... 2013/05/14 02:33:47 8: multiplying done; shifting... 2013/05/14 02:33:47 8: not shifting 2013/05/14 02:33:47 9: multiplying... gc2(1): 0+0+0 ms, 0 -> 0 MB 206 -> 144 (229-85) objects, 0(0) handoff, 0(0) stea l, 0/0/0 yields 2013/05/14 02:33:47 9: multiplying done; shifting... 2013/05/14 02:33:47 9: not shifting 2013/05/14 02:33:47 10: multiplying... 2013/05/14 02:33:47 10: multiplying done; shifting... 2013/05/14 02:33:47 10: not shifting 2013/05/14 02:33:47 11: multiplying... gc3(1): 0+0+0 ms, 1 -> 1 MB 154 -> 144 (240-96) objects, 0(0) handoff, 0(0) stea l, 0/0/0 yields 2013/05/14 02:33:47 11: multiplying done; shifting... 2013/05/14 02:33:47 11: not shifting 2013/05/14 02:33:47 12: multiplying... gc4(1): 0+0+0 ms, 2 -> 2 MB 150 -> 145 (247-102) objects, 0(0) handoff, 0(0) ste al, 0/0/0 yields 2013/05/14 02:33:48 12: multiplying done; shifting... 2013/05/14 02:33:48 12: not shifting 2013/05/14 02:33:48 13: multiplying... gc5(1): 0+0+0 ms, 4 -> 3 MB 150 -> 145 (253-108) objects, 0(0) handoff, 0(0) steal, 0/0/0 yields 2013/05/14 02:34:00 13: multiplying done; shifting... 2013/05/14 02:34:00 13: not shifting 2013/05/14 02:34:00 14: multiplying... gc6(1): 0+0+0 ms, 7 -> 6 MB 149 -> 144 (258-114) objects, 0(0) handoff, 0(0) ste al, 0/0/0 yields SIGQUIT: quit PC=0x229fb Which compiler are you using (5g, 6g, 8g, gccgo)? Whatever go build on go 1.1 on x86 OS X uses. Which operating system are you using? OS X Which version are you using? (run 'go version') go 1.1 (homebrew)