Bug #60228 for BerkeleyDB: FD leak in -ErrFile option to Env?

O/S: Debian 5.0 (stable) Perl: 5.10.0 BerkeleyDB: 0.42 Dear Mr Marquess, Thanks very much for maintaining the BerkeleyDB module --- I find it extremely useful in a range of scripts. I'm writing to report a rather difficult-to-pin-down problem whereby I run out of file descriptors when using BerkeleyDB and IPC::Run3 together. If I open an environment with the -ErrFile switch set to *STDERR and then immediately *close* that environment (!), every subsequent invocation of run3 leaks two file descriptors. Without the -ErrFile option no such problem occurs. The attached code exhibits the failure (I use /proc/.../fd in order to quickly find out what file descriptors my process has open, so the code should be run under a fairly modern Linux; without that feature though, it should still be possible to observe failure just by waiting for the script to run out of handles). I seem to be able to work around this using system() instead of run3(), so it's not a crucial issue but I'd be curious to know what the root cause is. It could certainly also be a problem with run3() rather than BerkeleyDB --- the fact that tweaking BDB flags controls the failure is what leads me to write to you first. I'm aware that BDB shouldn't be used in conjunction with fork() (which I think run3() uses), but in the C world I've worked around this constraint in the past by closing BDB environments and databases before forking, and re-opening afterward; it would appear that that trick doesn't work here, since I've already closed my environment before the run3() calls start to leak. Am I doing anything obvious wrong, or do you think there's something to this? Best regards, Conrad Hughes -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

#!/usr/bin/perl # Demonstrates a leak in BerkeleyDB -ErrFile: comment out the -ErrFile line, # and this script executes completely; otherwise, it will show an ever- # increasing number of file descriptors in use and, if your default max fds is # 1023, eventually die. # This is intended for use on a modern linux, supporting /proc/.../fd and # /dev/null. use strict; use warnings; use IPC::Run3; use BerkeleyDB; my $tmpdir = 'tmpdir'; mkdir $tmpdir unless -d $tmpdir; my $env = BerkeleyDB::Env->new( -Home => $tmpdir, -ErrFile => *STDERR, # Comment this line out and the leak vanishes -Flags => DB_CREATE ) or die $BerkeleyDB::Error; $env->close(); $env = undef; my $ufd = used_fds(); for(0 .. 511) { run3 ['cat', '/dev/null'], \undef, 'tmpdir/stdout', 'tmpdir/stderr'; my $nufd = used_fds(); print "$ufd -> $nufd descriptors in use.\n"; $ufd = $nufd; } sub used_fds { opendir DIR, "/proc/$$/fd" or die "Couldn't open /proc/$$/fd: $!"; my @entries = readdir(DIR); closedir DIR; @entries - 2 }