As proof of concept, provide an alternate implementation based on POSIX
semaphores. Also push the SysV shared-memory implementation into a
separate file so that it can be replaced conveniently.
was in the thread "make BufferGetBlockNumber() a macro". Tom
objected to the original patch, so I prepared a new one which
doesn't change BufferGetBlockNumber() into a macro, it just
cleans up some comments and fixes an assertion. The patch
is attached.
Neil Conway
for Solaris on SPARC. Scott Brunza (sbrunza@sonalysts.com) gets
credit for identifying the issue, making the change, and doing
the regression tests.
Earlier testing on 7.2rc2 and 7.2 showed performance gains of
1% to 10% on pgbench, osdb-pg, and some locally developed apps.
Solaris Intimate Shared Memory is described in "SOLARIS INTERNALS
Core Kernel Components" by Jim Mauro and Richard McDougall,
Copyright 2001 Sun Microsystem, Inc. ISBN 0-13-022496-0
P.J. "Josh" Rovero
The patch enables the mips2 ISA for the ll/sc operations, and then restores
it when done. The kernel/libc emulation code will take over on CPUs without
ll/sc, and on CPUs with it, it'll use the operations provided by the CPU.
Combined with the earlier fix (removing -mips2), postgresql builds again on
mips and mipsel. The patch is against 7.2-7.
Oliver Elphick
o Change all current CVS messages of NOTICE to WARNING. We were going
to do this just before 7.3 beta but it has to be done now, as you will
see below.
o Change current INFO messages that should be controlled by
client_min_messages to NOTICE.
o Force remaining INFO messages, like from EXPLAIN, VACUUM VERBOSE, etc.
to always go to the client.
o Remove INFO from the client_min_messages options and add NOTICE.
Seems we do need three non-ERROR elog levels to handle the various
behaviors we need for these messages.
Regression passed.
now just below FATAL in server_min_messages. Added more text to
highlight ordering difference between it and client_min_messages.
---------------------------------------------------------------------------
REALLYFATAL => PANIC
STOP => PANIC
New INFO level the prints to client by default
New LOG level the prints to server log by default
Cause VACUUM information to print only to the client
NOTICE => INFO where purely information messages are sent
DEBUG => LOG for purely server status messages
DEBUG removed, kept as backward compatible
DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1 added
DebugLvl removed in favor of new DEBUG[1-5] symbols
New server_min_messages GUC parameter with values:
DEBUG[5-1], INFO, NOTICE, ERROR, LOG, FATAL, PANIC
New client_min_messages GUC parameter with values:
DEBUG[5-1], LOG, INFO, NOTICE, ERROR, FATAL, PANIC
Server startup now logged with LOG instead of DEBUG
Remove debug_level GUC parameter
elog() numbers now start at 10
Add test to print error message if older elog() values are passed to elog()
Bootstrap mode now has a -d that requires an argument, like postmaster
removes any empty chunks, the chunk previously added won't be there
anymore, so it's possible there is zero free space in the rel's page list
afterwards. Must loop back and rerun the part that adds a chunk to
the list.
to prevent spreading of corruption when page header pointers are bad.
Merge PageZero into PageInit, since it was never used separately, and
remove separate memset calls used at most other PageInit call points.
Remove IndexPageCleanup, which wasn't used at all.
granted the lock when awakened; the signal now only means that the lock
is potentially available. The waiting process must retry its attempt
to get the lock when it gets to run. This allows the lock releasing
process to re-acquire the lock later in its timeslice. Since LWLocks
are usually held for short periods, it is possible for a process to
acquire and release the same lock many times in a timeslice. The old
spinlock-based implementation of these locks allowed for that; but the
original coding of LWLock would force a process swap for each acquisition
if there was any contention. Although this approach reopens the door to
process starvation (a waiter might repeatedly fail to get the lock),
the odds of that being a big problem seem low, and the performance cost
of the previous approach is considerable.
'volatile' pointers to access those structures, so that optimizing
compilers will not decide to move the structure accesses outside of the
spinlock-acquire-to-spinlock-release sequence. There are no known bugs
in these uses at present, but based on bad experience with lwlock.c,
it seems prudent to ensure that we protect these other uses too.
Per pghackers discussion around 12-Dec. (Note: it should not be
necessary to worry about structures protected by LWLocks, since the
LWLock acquire and release operations are not inline macros.)
should be accounted for in the PROC_SEM_MAP_ENTRIES() macro. Otherwise
the ports that rely on this macro to size data structures are broken.
Mea culpa.
so that only one signal number is used not three. Flags in shared
memory tell the reason(s) for the current signal. This method is
extensible to handle more signal reasons without chewing up even more
signal numbers, but the immediate reason is to keep pg_pwd reloads
separate from SIGHUP processing in the postmaster.
Also clean up some problems in the postmaster with delayed response to
checkpoint status changes --- basically, it wouldn't schedule a checkpoint
if it wasn't getting connection requests on a regular basis.
never overwrite adjacent pages with copied data, even if page header
and/or item pointers are already corrupt. Change inspired by trouble
report from Alvaro Herrera.
readability. Bizarre '(long *) TRUE' return convention is gone,
in favor of just raising an error internally in dynahash.c when
we detect hashtable corruption. HashTableWalk is gone, in favor
of using hash_seq_search directly, since it had no hope of working
with non-LONGALIGNable datatypes. Simplify some other code that was
made undesirably grotty by promixity to HashTableWalk.
portability issues). Caller-visible data structures are now allocated
on MAXALIGN boundaries, allowing safe use of datatypes wider than 'long'.
Rejigger hash_create API so that caller specifies size of key and
total size of entry, not size of key and size of rest of entry.
This simplifies life considerably since each number is just a sizeof(),
and padding issues etc. are taken care of automatically.
upper limit on what we will believe from sysconf(_SC_OPEN_MAX). The
default value is 1000, so that under ordinary conditions it won't
affect the behavior. But on platforms where the kernel promises far
more than it can deliver, this can be used to prevent running out of
file descriptors. See numerous past discussions, eg, pgsql-hackers
around 23-Dec-2000.
existing lock manager and spinlocks: it understands exclusive vs shared
lock but has few other fancy features. Replace most uses of spinlocks
with lightweight locks. All remaining uses of spinlocks have very short
lock hold times (a few dozen instructions), so tweak spinlock backoff
code to work efficiently given this assumption. All per my proposal on
pghackers 26-Sep-01.
a hung client or lost connection can't indefinitely block a postmaster
child (not to mention the possibility of deliberate DoS attacks).
Timeout is controlled by new authentication_timeout GUC variable,
which I set to 60 seconds by default ... does that seem reasonable?
for them, and making them just wastes time during backend startup/shutdown.
Also, remove compile-time MAXBACKENDS limit per long-ago proposal.
You can now set MaxBackends as high as your kernel can stand without
any reconfiguration/recompilation.
available in freeSemMap. As noted by Tatsuo, this is now a likely
scenario for detecting MaxBackends-exceeded; if MaxBackends is a multiple
of PROC_NSEMS_PER_SET then we will fail here and not in sinval.c. The
cleanup path did not work correctly before, anyway.
system. Some systems did not understand the 'l' section, and in general
it wasn't entirely appropriate.
On SCO OpenServer, the man pages won't be installed at all until someone
figures out their man system.
Tom Lane
Bruce Momjian
Peter Eisentraut