我在一台32GB内存的机器上运行postgresql 9.3，交换时为0。最多可连接200个客户端。盒子上还有另外1个4GB进程。如何解释此错误日志消息？如何防止内存不足错误？允许交换？为机器添加更多内存？允许更少客户端连接？调整设置？
示例pg_top：
last pid: 6607; load avg: 3.59, 2.32, 2.61; up 16+09:17:29 20:49:51
113 processes: 1 running, 111 sleeping, 1 uninterruptable
CPU states: 22.5% user, 0.0% nice, 4.9% system, 63.2% idle, 9.4% iowait
Memory: 29G used, 186M free, 7648K buffers, 23G cached
DB activity: 2479 tps, 1 rollbs/s, 217 buffer r/s, 99 hit%, 11994 row r/s, 3820 row w/s
DB I/O: 0 reads/s, 0 KB/s, 0 writes/s, 0 KB/s
DB disk: 149.8 GB total, 46.7 GB free (68% used)
Swap:
示例顶部显示了该框中唯一的其他重要4GB进程：
top - 21:05:09 up 16 days, 9:32, 2 users, load average: 2.73, 2.91, 2.88
Tasks: 247 total, 3 running, 244 sleeping, 0 stopped, 0 zombie
%Cpu(s): 22.1 us, 4.1 sy, 0.0 ni, 62.9 id, 9.8 wa, 0.0 hi, 0.7 si, 0.3 st
KiB Mem: 30827220 total, 30642584 used, 184636 free, 7292 buffers
KiB Swap: 0 total, 0 used, 0 free. 23449636 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7407 postgres 20 0 7604928 10172 7932 S 29.6 0.0 2:51.27 postgres
10469 postgres 20 0 7617716 176032 160328 R 11.6 0.6 0:01.48 postgres
10211 postgres 20 0 7630352 237736 208704 S 10.6 0.8 0:03.64 postgres
18202 elastic+ 20 0 8726984 4.223g 4248 S 9.6 14.4 883:06.79 java
9711 postgres 20 0 7619500 354188 335856 S 7.0 1.1 0:08.03 postgres
3638 postgres 20 0 7634552 1.162g 1.127g S 6.6 4.0 0:50.42 postgres
postgresql.conf中：
max_connections = 1000 # (change requires restart)
shared_buffers = 7GB # min 128kB
work_mem = 40MB # min 64kB
maintenance_work_mem = 1GB # min 1MB
effective_cache_size = 20GB
....
日志：
ERROR: out of memory
DETAIL: Failed on request of size 67108864.
STATEMENT: SELECT "package_texts".* FROM "package_texts" WHERE "package_texts"."id" = $1 LIMIT 1
TopMemoryContext: 798624 total in 83 blocks; 11944 free (21 chunks); 786680 used
TopTransactionContext: 8192 total in 1 blocks; 7328 free (0 chunks); 864 used
Prepared Queries: 253952 total in 5 blocks; 136272 free (18 chunks); 117680 used
Type information cache: 24240 total in 2 blocks; 3744 free (0 chunks); 20496 used
Operator lookup cache: 24576 total in 2 blocks; 11888 free (5 chunks); 12688 used
TableSpace cache: 8192 total in 1 blocks; 3216 free (0 chunks); 4976 used
MessageContext: 8192 total in 1 blocks; 6976 free (0 chunks); 1216 used
Operator class cache: 8192 total in 1 blocks; 1680 free (0 chunks); 6512 used
smgr relation table: 24576 total in 2 blocks; 5696 free (4 chunks); 18880 used
TransactionAbortContext: 32768 total in 1 blocks; 32736 free (0 chunks); 32 used
Portal hash: 8192 total in 1 blocks; 1680 free (0 chunks); 6512 used
PortalMemory: 8192 total in 1 blocks; 7888 free (0 chunks); 304 used
PortalHeapMemory: 1024 total in 1 blocks; 568 free (0 chunks); 456 used
ExecutorState: 32928 total in 3 blocks; 15616 free (5 chunks); 17312 used
printtup: 34002024 total in 2 blocks; 7056 free (7 chunks); 33994968 used
ExprContext: 0 total in 0 blocks; 0 free (0 chunks); 0 used
ExprContext: 0 total in 0 blocks; 0 free (0 chunks); 0 used
ExprContext: 0 total in 0 blocks; 0 free (0 chunks); 0 used
Relcache by OID: 24576 total in 2 blocks; 12832 free (3 chunks); 11744 used
CacheMemoryContext: 1372624 total in 24 blocks; 38832 free (0 chunks); 1333792 used
CachedPlanSource: 7168 total in 3 blocks; 3080 free (1 chunks); 4088 used
CachedPlanQuery: 7168 total in 3 blocks; 2992 free (1 chunks); 4176 used
CachedPlanSource: 15360 total in 4 blocks; 7128 free (5 chunks); 8232 used
CachedPlanQuery: 15360 total in 4 blocks; 3320 free (1 chunks); 12040 used
CachedPlanSource: 3072 total in 2 blocks; 552 free (0 chunks); 2520 used
CachedPlanQuery: 7168 total in 3 blocks; 1592 free (1 chunks); 5576 used
CachedPlanSource: 3072 total in 2 blocks; 536 free (0 chunks); 2536 used
... 2 Thousand snipped lines of CachedPlans ...
CachedPlanSource: 15360 total in 4 blocks; 7128 free (5 chunks); 8232 used
CachedPlanQuery: 15360 total in 4 blocks; 3320 free (1 chunks); 12040 used
CachedPlanSource: 7168 total in 3 blocks; 3880 free (3 chunks); 3288 used
CachedPlanQuery: 7168 total in 3 blocks; 4032 free (1 chunks); 3136 used
CachedPlanSource: 7168 total in 3 blocks; 3936 free (3 chunks); 3232 used
CachedPlanQuery: 7168 total in 3 blocks; 4032 free (1 chunks); 3136 used
CachedPlanSource: 7168 total in 3 blocks; 3080 free (1 chunks); 4088 used
CachedPlanQuery: 7168 total in 3 blocks; 2992 free (1 chunks); 4176 used
CachedPlanSource: 7168 total in 3 blocks; 3872 free (2 chunks); 3296 used
CachedPlanQuery: 7168 total in 3 blocks; 4032 free (1 chunks); 3136 used
pg_toast_17305_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
index_package_raises_on_natural_key: 3072 total in 2 blocks; 1648 free (1 chunks); 1424 used
index_package_extensions_on_natural_key: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
index_package_mixins_on_natural_key: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
index_package_mixins_on_includes_id: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
package_texts_pkey: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
index_package_file_objects_on_natural_key: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
index_package_symbols_on_natural_key: 3072 total in 2 blocks; 1136 free (1 chunks); 1936 used
index_package_symbols_on_full_name: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
index_package_symbols_on_alias_for_id: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
package_symbols_pkey: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_toast_17313_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
index_packages_on_natural_key: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
packages_pkey: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
index_package_files_on_natural_key: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
package_files_pkey: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_toast_2619_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
index_projects_on_user_id: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
index_projects_on_type: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
index_projects_on_name_and_type: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
index_projects_on_claim_ticket: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
ruby_gem_metadata_pkey: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_constraint_contypid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_constraint_conrelid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_constraint_conname_nsp_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_attrdef_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_attrdef_adrelid_adnum_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_index_indrelid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_db_role_setting_databaseid_rol_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_opclass_am_name_nsp_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_foreign_data_wrapper_name_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_enum_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_class_relname_nsp_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_foreign_server_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_statistic_relid_att_inh_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_cast_source_target_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_language_name_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_collation_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_amop_fam_strat_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_index_indexrelid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_ts_template_tmplname_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_ts_config_map_index: 3072 total in 2 blocks; 1784 free (2 chunks); 1288 used
pg_opclass_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_foreign_data_wrapper_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_event_trigger_evtname_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_ts_dict_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_event_trigger_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_conversion_default_index: 3072 total in 2 blocks; 1784 free (2 chunks); 1288 used
pg_operator_oprname_l_r_n_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_trigger_tgrelid_tgname_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_enum_typid_label_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_ts_config_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_user_mapping_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_opfamily_am_name_nsp_index: 3072 total in 2 blocks; 1784 free (2 chunks); 1288 used
pg_foreign_table_relid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_type_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_aggregate_fnoid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_constraint_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_rewrite_rel_rulename_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_ts_parser_prsname_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_ts_config_cfgname_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_ts_parser_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_operator_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_namespace_nspname_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_ts_template_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_amop_opr_fam_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_default_acl_role_nsp_obj_index: 3072 total in 2 blocks; 1784 free (2 chunks); 1288 used
pg_collation_name_enc_nsp_index: 3072 total in 2 blocks; 1784 free (2 chunks); 1288 used
pg_range_rngtypid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_ts_dict_dictname_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_type_typname_nsp_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_opfamily_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_class_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_proc_proname_args_nsp_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_attribute_relid_attnum_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_proc_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_language_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_namespace_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_amproc_fam_proc_index: 3072 total in 2 blocks; 1736 free (2 chunks); 1336 used
pg_foreign_server_name_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_attribute_relid_attnam_index: 1024 total in 1 blocks; 16 free (0 chunks); 1008 used
pg_conversion_oid_index: 1024 total in 1 blocks; 200 free (0 chunks); 824 used
pg_user_mapping_user_server_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_conversion_name_nsp_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_authid_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_auth_members_member_role_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_tablespace_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_database_datname_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_auth_members_role_member_index: 1024 total in 1 blocks; 64 free (0 chunks); 960 used
pg_database_oid_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
pg_authid_rolname_index: 1024 total in 1 blocks; 152 free (0 chunks); 872 used
MdSmgr: 24576 total in 2 blocks; 13984 free (0 chunks); 10592 used
ident parser context: 0 total in 0 blocks; 0 free (0 chunks); 0 used
hba parser context: 7168 total in 3 blocks; 304 free (1 chunks); 6864 used
LOCALLOCK hash: 8192 total in 1 blocks; 1680 free (0 chunks); 6512 used
Timezones: 83472 total in 2 blocks; 3744 free (0 chunks); 79728 used
ErrorContext: 8192 total in 1 blocks; 8160 free (6 chunks); 32 used
答案 0 :(得分：2)
如果我正确地读取了您的顶部输出，那么当您内存不足时，它就不会被拍摄。
实际错误似乎很好 - 它没有请求大量内存，因此可能是机器在那时没有内存。
让我们快速浏览一下您的设置：
max_connections = 1000 # (change requires restart)
work_mem = 40MB # min 64kB
所以 - 您认为您可以支持1000个并发查询，每个查询使用10 + 40MB（有些可能使用40MB的倍数，但让它们合理）。所以 - 这表明你的机器有＆gt; 500核心，说100GB的RAM。事实并非如此。
所以 - 获取核心数量并加倍 - 这是最大连接数的合理值。这将允许您对每个核心进行一次查询，而另一个正在等待I / O.然后，如果需要（pgbouncer / Java的连接池），请在数据库前面放置一个连接池。
然后，如果需要，您甚至可以考虑增加work_mem。
哦 - 在没有启用交换的情况下运行是完全合理的。一旦你开始交换，无论如何在数据库使用方面都处于痛苦的世界。
编辑：展开work_mem vs shared
如有疑问，请始终参考documentation。
shared_buffers值，正如后端之间共享的名称所示。 work_mem不仅适用于每个后端，而且实际上是每种类型。所以 - 如果一个查询在三个子查询上进行排序，那么它可能会使用三到四倍的数量。
答案 1 :(得分：-1)
重启服务器对我有帮助