On Wed, 11 Jul 2018 14:06:17 +0100 Stefan Hajnoczi <stefa...@gmail.com> wrote:
> On Mon, Jul 09, 2018 at 03:45:49PM +0200, Cornelia Huck wrote: > > Hi, > > > > I recently noticed that iotest 147 was hanging on my laptop, but worked > > fine on my s390x LPAR. Turned out that the architecture was a red > > herring; on both platforms, things fail with the 'simple' trace backend > > and work with e.g. the 'log' trace backend. Some details on the > > failures with the 'simple' backend: > > > > - The first run of 147 passes. However, there are two processes hanging > > around, one using a unix socket and one using an inet socket: > > > > cohuck 22912 0.0 0.0 156580 3836 ? Ss 14:32 0:00 > > /home/cohuck/git/qemu/build/tests/qemu-iotests/../../qemu-nbd --fork -f > > qcow2 /home/cohuck/git/qemu/build/tests/qemu-iotests/scratch/test.img -p > > 10811 > > cohuck 22925 0.0 0.0 156580 3840 ? Ss 14:32 0:00 > > /home/cohuck/git/qemu/build/tests/qemu-iotests/../../qemu-nbd --fork -f > > qcow2 /home/cohuck/git/qemu/build/tests/qemu-iotests/scratch/test.img -k > > /home/cohuck/git/qemu/build/tests/qemu-iotests/scratch/nbd.socket > > > > Attaching a gdb shows that we seem to be waiting on flushing: > > > > (gdb) bt > > #0 0x00007f461c078b99 in syscall () from /lib64/libc.so.6 > > #1 0x00007f461d13650f in g_cond_wait () from /lib64/libglib-2.0.so.0 > > #2 0x0000560cf3a1caf2 in flush_trace_file (wait=255) > > at /home/cohuck/git/qemu/trace/simple.c:139 > > #3 st_flush_trace_buffer () at /home/cohuck/git/qemu/trace/simple.c:374 > > #4 0x00007f461bfc01d8 in __run_exit_handlers () from /lib64/libc.so.6 > > #5 0x00007f461bfc022a in exit () from /lib64/libc.so.6 > > #6 0x0000560cf392eb7e in main (argc=<optimized out>, argv=<optimized out>) > > at /home/cohuck/git/qemu/qemu-nbd.c:1076 > > > > (for both processes) > > Please also print backtraces for the other threads: > > (gdb) thread apply all bt > > There should be another thread in writeout_thread() so I'm surprised > that flush_trace_file() is getting stuck in g_cond_wait(). I'll re-run to check, but there was only one thread in the process in question.