Обсуждение: pg_test_fsync crashes on systems with POSIX signal handling
On my old HPUX box: $ ./pg_test_fsync 2 seconds per test Direct I/O is not supported on this platform. Compare file sync methods using one 8kB write: (in wal_sync_method preference order, except fdatasync is Linux's default) open_datasync 165.122 ops/sec ( 6056 microsecs/op) fdatasync Alarm call $ echo $? 142 -- that's SIGALRM The reason it's failing is that according to the traditional (not BSD) definition of signal(2), the signal handler is reset to SIG_DFL when the signal is delivered. So the second occurrence of SIGALRM doesn't call the signal handler but just crashes the process. The quick-and-dirty fix for this is to just copy pqsignal() into pg_test_fsync, and use that instead of calling signal() directly. I wonder though if we shouldn't move that function into libpgport. Thoughts? regards, tom lane
On Fri, Mar 15, 2013 at 03:05:54PM -0400, Tom Lane wrote: > On my old HPUX box: > > $ ./pg_test_fsync > 2 seconds per test > Direct I/O is not supported on this platform. > > Compare file sync methods using one 8kB write: > (in wal_sync_method preference order, except fdatasync > is Linux's default) > open_datasync 165.122 ops/sec ( 6056 microsecs/op) > fdatasync Alarm call > $ echo $? > 142 -- that's SIGALRM > > The reason it's failing is that according to the traditional (not BSD) > definition of signal(2), the signal handler is reset to SIG_DFL when the > signal is delivered. So the second occurrence of SIGALRM doesn't call > the signal handler but just crashes the process. > > The quick-and-dirty fix for this is to just copy pqsignal() into > pg_test_fsync, and use that instead of calling signal() directly. > I wonder though if we shouldn't move that function into libpgport. > Thoughts? Well, the Win32 signal handler is already in port, so moving the Unix one seems to make sense, i.e. the comment above pgsignal says: /* Win32 signal handling is in backend/port/win32/signal.c */ -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
Bruce Momjian <bruce@momjian.us> writes: > On Fri, Mar 15, 2013 at 03:05:54PM -0400, Tom Lane wrote: >> The quick-and-dirty fix for this is to just copy pqsignal() into >> pg_test_fsync, and use that instead of calling signal() directly. >> I wonder though if we shouldn't move that function into libpgport. >> Thoughts? > Well, the Win32 signal handler is already in port, so moving the Unix > one seems to make sense, i.e. the comment above pgsignal says: > /* Win32 signal handling is in backend/port/win32/signal.c */ Done, though it was a bit more painful than I expected --- I seem to have guessed completely wrong about where the portability hazards were. Good thing we have a buildfarm. regards, tom lane