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 [email protected]]
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 =3 shard_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：‘
[root@server ~]# ps aux | grep post root 0.0 0.0 pts/ S : : su - postgres postgres 0.0 0.0 pts/ S+ : : -bash postgres 0.0 0.2 pts/ S : : /usr/local/pgsql/bin/postgres -D /gao/data postgres 0.4 3.0 ? Ss : : postgres: writer process postgres 0.2 0.1 ? Ds : : postgres: wal writer process postgres 0.0 0.0 ? Ss : : postgres: autovacuum launcher process postgres 0.0 0.0 ? Ss : : postgres: stats collector process root 0.0 0.0 pts/ S : : su - postgres postgres 0.0 0.0 pts/ S : : -bash postgres 0.0 0.0 pts/ S+ : : ./psql postgres 14.8 80.2 ? Ds : : postgres: postgres postgres [local] INSERT root 0.0 0.0 pts/ S+ : : 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 ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently ( seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: background writer process (PID ) was terminated by signal : 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 -- :: CST
LOG: database system was not properly shut down; automatic recovery in progress
LOG: consistent recovery state reached at /B7657BD0
LOG: redo starts at /B60FE2B8
LOG: unexpected pageaddr /B044C000 in log file , segment , offset
LOG: redo done at /B844B940
LOG: autovacuum launcher started
LOG: database system is ready to accept connections
各个进程都重新生成了：
[root@server ~]# ps aux | grep post
root 0.0 0.0 pts/ S : : su - postgres
postgres 0.0 0.0 pts/ S+ : : -bash
postgres 0.0 0.5 pts/ S : : /usr/local/pgsql/bin/postgres -D /gao/data
root 0.0 0.0 pts/ S : : su - postgres
postgres 0.0 0.0 pts/ S : : -bash
postgres 0.0 0.0 pts/ S+ : : ./psql
postgres 0.0 0.0 ? Ss : : postgres: writer process
postgres 0.0 0.0 ? Ss : : postgres: wal writer process
postgres 0.0 0.1 ? Ss : : postgres: autovacuum launcher process
postgres 0.0 0.0 ? Ss : : postgres: stats collector process
root 0.0 0.0 pts/ R+ : : grep post
[root@server ~]#
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 [email protected]]
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
磨砺技术珠矶，践行数据之道，追求卓越价值