On February 14, 2019 17:34, Max Kirillov wrote: > To: Randall S. Becker <rsbecker@xxxxxxxxxxxxx> > Cc: 'Johannes Schindelin via GitGitGadget' <gitgitgadget@xxxxxxxxx>; > git@xxxxxxxxxxxxxxx; 'Junio C Hamano' <gitster@xxxxxxxxx>; 'Max Kirillov' > <max@xxxxxxxxxx> > Subject: Re: [PATCH 0/1] Fix hang in t5562, introduced in v2.21.0-rc1 > > On Thu, Feb 14, 2019 at 05:17:26PM -0500, Randall S. Becker wrote: > > Unfortunately, subtest 13 still hangs on NonStop, even with this > > patch, so our Pipeline still hangs. I'm glad it's better on Azure, but > > I don't think this actually addresses the root cause of the hang. This > > is now the fourth attempt at fixing this. Is it possible this is not > > the test that is failing, but actually the git-http-backend? The code > > is not in a loop, if that helps. It is not consuming any significant > > cycles. I don't know that part of the code at all, sadly. The code is > > here: > > > > * in the operating system from here up * > > cleanup_children + 0x5D0 (UCr) > > ... so does the process which the stack was taken from has any children > processes still? > > I could imagine if a child somehow manages to end up in uninterruptible > sleep, then probably it would never complete this way, wouldn't it? Here is the full set of traces (from subtest 6, which just hung). There are no I/O errors reported on any pipe or file descriptor. There is one git process waiting for a read to occur but no one is doing any writing. Most processes are sitting in waitpid, except for the initiating git, which is waiting on a read that never receives data, so everyone is asleep and hung. The git process sitting in read is reading from a PIPE, not a file. There are no other processes involved in the test that I can see. Perl (waiting for output to be read): waitpid + 0x130 (SLr) $n_EnterPriv + 0x280 (Milli) Perl_wait4pid + 0x130 (UCr) Perl_my_pclose + 0x4C0 (UCr) Perl_io_close + 0x180 (UCr) Perl_do_close + 0x620 (UCr) Perl_pp_close + 0xA70 (UCr) Perl_runops_standard + 0xF0 (UCr) S_run_body + 0x870 (UCr) perl_run + 0x2D0 (UCr) main + 0x3D0 (UCr) git-http-backend: waitpid + 0x320 (SLr) $n_EnterPriv + 0x280 (Milli) cleanup_children + 0x5D0 (UCr) cleanup_children_on_exit + 0x70 (UCr) git_atexit_dispatch + 0x200 (UCr) __process_atexit_functions + 0xA0 (DLL zcredll) CRE_TERMINATOR_ + 0xB50 (DLL zcredll) exit + 0x2A0 (DLL zcrtldll) die_webcgi + 0x240 (UCr) die_errno + 0x360 (UCr) write_or_die + 0x1C0 (UCr) end_headers + 0x1A0 (UCr) die_webcgi + 0x220 (UCr) die + 0x320 (UCr) inflate_request + 0x520 (UCr) run_service + 0xC20 (UCr) service_rpc + 0x530 (UCr) cmd_main + 0xD00 (UCr) main + 0x190 (UCr) git (one of them): read64_ + 0x140 (SLr) $n_EnterPriv + 0x280 (Milli) xread + 0x130 (UCr) read_in_full + 0x130 (UCr) get_packet_data + 0x4B0 (UCr) packet_read_with_status + 0x230 (UCr) packet_reader_read + 0x310 (UCr) receive_needs + 0x300 (UCr) upload_pack + 0x680 (UCr) cmd_upload_pack + 0x830 (UCr) run_builtin + 0x980 (UCr) handle_builtin + 0x570 (UCr) run_argv + 0x210 (UCr) cmd_main + 0x710 (UCr) main + 0x190 (UCr) bash: waitpid + 0x130 (SLr) $n_EnterPriv + 0x280 (Milli) waitchld + 0x1F0 (UCr) wait_for + 0xFD0 (UCr) execute_command_internal + 0x1990 (UCr) execute_command + 0xC0 (UCr) reader_loop + 0x4F0 (UCr) main + 0x1140 (UCr) git (the other one): waitpid + 0x130 (SLr) $n_EnterPriv + 0x280 (Milli) wait_or_whine + 0xE0 (UCr) finish_command + 0x100 (UCr) run_command + 0x1F0 (UCr) execv_dashed_external + 0x800 (UCr) run_argv + 0x250 (UCr) cmd_main + 0x710 (UCr) main + 0x190 (UCr)
