PostreSQL崩溃试验全记录
磨砺技术珠矶，践行数据之道，追求卓越价值回到上一级页面： PostgreSQL基础知识与基本操作索引页 回到顶级页面：PostgreSQL索引页
[作者 高健@博客园luckyjackgao@gmail.com]
由于客户提到，运行某些大运算量批处理时，PostgreSQL突发性使用大量资源的问题，
进行了如下的调查，发现确实发生了崩溃。PostgreSQL 需要资源控制方案啊。
现在正在考虑是否必须要用 os 级别的限制方案：
过程如下：
测试环境：
内存：大约1024MB
postgresql.conf 设定：
使用缺省值：checkpoint_segments =3shard_buffers=32MB
这些是有意为之，就是想看看数据量大、shared_buffer小的状况：
建立表(一条记录大约1024字节)：
postgres=# create table test01(id integer, val char(1024));
向表中插入大量数据(总共插入2400MB)
postgres=# insert into test01 values(generate_series(1,2457600),repeat( chr(int4(random()*26)+65),1024));
插入操作会花费一些时间，此时用ps 命令看PostgreSQL个进程对内存使用状况：‘
# ps aux | grep post
root 31800.00.0 105296 712 pts/1 S 16:31 0:00 su - postgres
postgres31810.00.070304 676 pts/1 S+ 16:31 0:00 -bash
postgres32190.00.2 1136442864 pts/1 S 16:32 0:00 /usr/local/pgsql/bin/postgres -D /gao/data
postgres32210.43.0 113724 35252 ? Ss 16:32 0:01 postgres: writer process
postgres32220.20.1 1136441616 ? Ds 16:32 0:00 postgres: wal writer process
postgres32230.00.0 1143801148 ? Ss 16:32 0:00 postgres: autovacuum launcher process
postgres32240.00.073332 472 ? Ss 16:32 0:00 postgres: stats collector process
root 32520.00.0 105296 712 pts/2 S 16:32 0:00 su - postgres
postgres32530.00.070304 676 pts/2 S 16:32 0:00 -bash
postgres32850.00.083488 740 pts/2 S+ 16:32 0:00 ./psql
postgres3286 14.8 80.2 2598332 924308 ? Ds 16:32 0:35 postgres: postgres postgres INSERT
root 33330.00.065424 812 pts/3 S+ 16:36 0:00 grep post
可以发现，INSERT操作正在消耗80%以上的内存。
再等片刻，发现psql端传来反馈：
WARNING:terminating connection because of crash of another server process
DETAIL:The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:In a moment you should be able to reconnect to the database and repeat your command.
The connection to the server was lost. Attempting reset: Failed.
!>
此时看看Log，可以看到：background writer (3321) 已经被干掉了，所有连接被重置。
LOG:autovacuum launcher started
LOG:database system is ready to accept connections
LOG:checkpoints are occurring too frequently (2 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (1 second apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (2 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (1 second apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (2 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (1 second apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (2 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (4 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (10 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (9 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (7 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (9 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (7 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (5 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (5 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (10 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (11 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (15 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (23 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (7 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (8 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (13 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (7 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (8 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (8 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (8 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (4 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (5 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:checkpoints are occurring too frequently (9 seconds apart)
HINT:Consider increasing the configuration parameter "checkpoint_segments".
LOG:background writer process (PID 3221) was terminated by signal 9: Killed
LOG:terminating any other active server processes
WARNING:terminating connection because of crash of another server process
DETAIL:The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:In a moment you should be able to reconnect to the database and repeat your command.
WARNING:terminating connection because of crash of another server process
DETAIL:The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:In a moment you should be able to reconnect to the database and repeat your command.
WARNING:terminating connection because of crash of another server process
DETAIL:The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:In a moment you should be able to reconnect to the database and repeat your command.
WARNING:terminating connection because of crash of another server process
DETAIL:The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:In a moment you should be able to reconnect to the database and repeat your command.
LOG:all server processes terminated; reinitializing
FATAL:the database system is in recovery mode
LOG:database system was interrupted; last known up at 2013-08-30 16:36:42 CST
LOG:database system was not properly shut down; automatic recovery in progress
LOG:consistent recovery state reached at 0/B7657BD0
LOG:redo starts at 0/B60FE2B8
LOG:unexpected pageaddr 0/B044C000 in log file 0, segment 184, offset 4505600
LOG:redo done at 0/B844B940
LOG:autovacuum launcher started
LOG:database system is ready to accept connections
各个进程都重新生成了：
# ps aux | grep post
root 31800.00.0 105296 660 pts/1 S 16:31 0:00 su - postgres
postgres31810.00.070304 628 pts/1 S+ 16:31 0:00 -bash
postgres32190.00.5 1136446276 pts/1 S 16:32 0:00 /usr/local/pgsql/bin/postgres -D /gao/data
root 32520.00.0 105296 660 pts/2 S 16:32 0:00 su - postgres
postgres32530.00.070304 628 pts/2 S 16:32 0:00 -bash
postgres32850.00.0834881144 pts/2 S+ 16:32 0:00 ./psql
postgres33480.00.0 113644 984 ? Ss 16:40 0:00 postgres: writer process
postgres33490.00.0 113644 732 ? Ss 16:40 0:00 postgres: wal writer process
postgres33500.00.1 1143361756 ? Ss 16:40 0:00 postgres: autovacuum launcher process
postgres33510.00.073332 580 ? Ss 16:40 0:00 postgres: stats collector process
root 33610.00.065420 796 pts/3 R+ 16:44 0:00 grep post
#
回到psql端再看，发现连接已经失效了：
!> \
Invalid command \. Try \? for help.
!> \dt;
You are currently not connected to a database.
!>
根据向社区提问，据说是因为OS级别的OOM错误发生,所以杀死了Postmaster进程。
总之，此种情况表明，如果没有对资源消费总量的控制，那么突发性的用户访问会导致崩溃的。
[作者 高健@博客园luckyjackgao@gmail.com]
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磨砺技术珠矶，践行数据之道，追求卓越价值
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