[HACKERS] Freeze on Cygwin w/ concurrency - Mailing list pgsql-hackers

"pgbench -i -s 50; pgbench -S -j2 -c16 -T900 -P5" freezes consistently on
Cygwin 2.2.1 and Cygwin 2.6.0.  (I suspect most other versions are affected.)
I've pinged[1] the Cygwin bug thread with some additional detail.  If a Cygwin
buildfarm member starts using --enable-tap-tests, you may see failures in the
pgbench test suite.  (lorikeet used --enable-tap-tests from 2017-03-18 to
2017-03-20, but it failed before reaching the pgbench test suite.)  Curious
that "make check" has too little concurrency to see more effects from this.


Frozen backends show a stack trace like this:

#0  0x000000007710139a in ntdll!ZwWriteFile () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
#1  0x000007fefd851b2b in WriteFile () from /cygdrive/c/Windows/system32/KERNELBASE.dll
#2  0x0000000076fb3576 in WriteFile () from /cygdrive/c/Windows/system32/kernel32.dll
#3  0x0000000180160c6c in transport_layer_pipes::write (this=<optimized out>, buf=<optimized out>, len=<optimized out>)
 at /usr/src/debug/cygwin-2.6.0-1/winsup/cygserver/transport_pipes.cc:224
 
#4  0x000000018015feb6 in client_request::send (this=0xffffa930, conn=0x6000e8290) at
/usr/src/debug/cygwin-2.6.0-1/winsup/cygserver/client.cc:134
#5  0x0000000180160591 in client_request::make_request (this=this@entry=0xffffa930) at
/usr/src/debug/cygwin-2.6.0-1/winsup/cygserver/client.cc:473
#6  0x0000000180114f79 in semop (semid=65540, sops=0xffffaa00, nsops=1) at
/usr/src/debug/cygwin-2.6.0-1/winsup/cygwin/sem.cc:125
#7  0x0000000180117a4b in _sigfe () at sigfe.s:35
#8  0x000000010063c81a in PGSemaphoreLock (sema=sema@entry=0x6ffffe06a18) at pg_sema.c:387
#9  0x00000001006a962b in LWLockAcquire (lock=lock@entry=0x6fff6774d80, mode=mode@entry=LW_SHARED) at lwlock.c:1286
#10 0x0000000100687d46 in BufferAlloc (foundPtr=0xffffab0b <incomplete sequence \367\377\006>, strategy=0x0,
blockNum=290,forkNum=MAIN_FORKNUM,    relpersistence=112 'p', smgr=0x6000ea588) at bufmgr.c:1012
 

The postmaster, also frozen, shows a stack trace like this:

#0  0x00000000771018ca in ntdll!ZwWaitForMultipleObjects () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
#1  0x000007fefd851420 in KERNELBASE!GetCurrentProcess () from /cygdrive/c/Windows/system32/KERNELBASE.dll
#2  0x0000000076fa1220 in WaitForMultipleObjects () from /cygdrive/c/Windows/system32/kernel32.dll
#3  0x0000000180120173 in child_info::sync (this=this@entry=0xffffc008, pid=4692, hProcess=@0xffffc1b0: 0x4b8,
howlong=howlong@entry=300000)  at /usr/src/debug/cygwin-2.6.0-1/winsup/cygwin/sigproc.cc:1010
 
#4  0x00000001800aa163 in frok::parent (this=0xffffc000, stack_here=0xffffbfa0 "") at
/usr/src/debug/cygwin-2.6.0-1/winsup/cygwin/fork.cc:501
#5  0x00000001800aaa05 in fork () at /usr/src/debug/cygwin-2.6.0-1/winsup/cygwin/fork.cc:607
#6  0x0000000180117a4b in _sigfe () at sigfe.s:35
#7  0x0000000100641618 in fork_process () at fork_process.c:61
#8  0x000000010063e80a in StartAutoVacWorker () at autovacuum.c:1436

The postmaster log eventually has:
    28 [main] postgres 4408 child_info::sync: wait failed, pid 4692, Win32 error 183   292 [main] postgres 4408 fork:
child4692 - died waiting for dll loading, errno 11
 


[1] https://cygwin.com/ml/cygwin/2017-03/msg00218.html