Hello,
We recently had many failed or lost connection problem to the mysql server. About 2-3 per hour during heavy peaks. We have a dedicated mysql server with 1 gig of RAM and 2 processor. The server is not swapping and the load is not a problem, 95% of the time under 0.05. We only have MyISAM tables.
I changed the default value of these 2 variables to:
net_read_timeout=60
connect_timeout=15
And it solved the problem. But this is not a very good thing to do. I am sure there is a problem which I am not seeing here. If you could help me find it!
my my.cnf is:
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
old_passwords=1
log-bin=/mysqlreplog/bin-log
server_id=1
log_slow_queries=/mysqlreplog/slow-queries.log
long_query_time=4
skip-locking
key_buffer = 256M
max_allowed_packet = 1M
table_cache = 256
net_read_timeout=60
connect_timeout=15
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
#set-variable = max_connections=500
max_connections=500
ft_min_word_len=3
expire_logs_days = 7
Try number of CPU’s*2 for thread_concurrency
thread_concurrency = 4
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
The current status of the server:
±----------------------------------±-----------+
| Variable_name | Value |
±----------------------------------±-----------+
| Aborted_clients | 1449 |
| Aborted_connects | 16 |
| Binlog_cache_disk_use | 0 |
| Binlog_cache_use | 0 |
| Bytes_received | 4086824150 |
| Bytes_sent | 205346791 |
| Com_admin_commands | 2699 |
| Com_alter_db | 0 |
| Com_alter_table | 2 |
| Com_analyze | 0 |
| Com_backup_table | 0 |
| Com_begin | 0 |
| Com_call_procedure | 0 |
| Com_change_db | 506467 |
| Com_change_master | 0 |
| Com_check | 0 |
| Com_checksum | 0 |
| Com_commit | 0 |
| Com_create_db | 0 |
| Com_create_function | 0 |
| Com_create_index | 0 |
| Com_create_table | 0 |
| Com_create_user | 0 |
| Com_dealloc_sql | 0 |
| Com_delete | 1852 |
| Com_delete_multi | 0 |
| Com_do | 0 |
| Com_drop_db | 0 |
| Com_drop_function | 0 |
| Com_drop_index | 0 |
| Com_drop_table | 0 |
| Com_drop_user | 0 |
| Com_execute_sql | 0 |
| Com_flush | 0 |
| Com_grant | 0 |
| Com_ha_close | 0 |
| Com_ha_open | 0 |
| Com_ha_read | 0 |
| Com_help | 0 |
| Com_insert | 22385 |
| Com_insert_select | 13 |
| Com_kill | 0 |
| Com_kill | 0 |
| Com_load | 0 |
| Com_load_master_data | 0 |
| Com_load_master_table | 0 |
| Com_lock_tables | 0 |
| Com_optimize | 7 |
| Com_preload_keys | 0 |
| Com_prepare_sql | 0 |
| Com_purge | 0 |
| Com_purge_before_date | 0 |
| Com_rename_table | 0 |
| Com_repair | 0 |
| Com_replace | 98458 |
| Com_replace_select | 0 |
| Com_reset | 0 |
| Com_restore_table | 0 |
| Com_revoke | 0 |
| Com_revoke_all | 0 |
| Com_rollback | 0 |
| Com_savepoint | 0 |
| Com_select | 317449 |
| Com_set_option | 106257 |
| Com_show_binlog_events | 0 |
| Com_show_binlogs | 14 |
| Com_show_charsets | 1086 |
| Com_show_collations | 1086 |
| Com_show_column_types | 0 |
| Com_show_create_db | 0 |
| Com_show_create_table | 383 |
| Com_show_databases | 1086 |
| Com_show_errors | 0 |
| Com_show_fields | 1185 |
| Com_show_grants | 563 |
| Com_show_innodb_status | 0 |
| Com_show_keys | 491 |
| Com_show_logs | 0 |
| Com_show_master_status | 0 |
| Com_show_ndb_status | 0 |
| Com_show_new_master | 0 |
| Com_show_open_tables | 0 |
| Com_show_privileges | 0 |
| Com_show_processlist | 0 |
| Com_show_slave_hosts | 0 |
| Com_show_slave_status | 0 |
| Com_show_status | 1 |
| Com_show_storage_engines | 0 |
| Com_show_tables | 4541 |
| Com_show_triggers | 0 |
| Com_show_variables | 3878 |
| Com_show_warnings | 60 |
| Com_slave_start | 0 |
| Com_slave_stop | 0 |
| Com_stmt_close | 0 |
| Com_stmt_execute | 0 |
| Com_stmt_fetch | 0 |
| Com_stmt_prepare | 0 |
| Com_stmt_reset | 0 |
| Com_stmt_send_long_data | 0 |
| Com_truncate | 0 |
| Com_unlock_tables | 0 |
| Com_update | 37100 |
| Com_update_multi | 1 |
| Com_xa_commit | 0 |
| Com_xa_end | 0 |
| Com_xa_prepare | 0 |
| Com_xa_recover | 0 |
| Com_xa_rollback | 0 |
| Com_xa_start | 0 |
| Compression | OFF |
| Connections | 808474 |
| Created_tmp_disk_tables | 7460 |
| Created_tmp_files | 119 |
| Created_tmp_tables | 34222 |
| Delayed_errors | 0 |
| Delayed_insert_threads | 0 |
| Delayed_writes | 0 |
| Flush_commands | 1 |
| Handler_commit | 0 |
| Handler_delete | 13597 |
| Handler_discover | 0 |
| Handler_prepare | 0 |
| Handler_read_first | 189631 |
| Handler_read_key | 26450608 |
| Handler_read_next | 1130806215 |
| Handler_read_prev | 2350760 |
| Handler_read_rnd | 896052 |
| Handler_read_rnd_next | 1100564513 |
| Handler_rollback | 0 |
| Handler_savepoint | 0 |
| Handler_savepoint_rollback | 0 |
| Handler_update | 560077 |
| Handler_write | 4616671 |
| Innodb_buffer_pool_pages_data | 20 |
| Innodb_buffer_pool_pages_dirty | 0 |
| Innodb_buffer_pool_pages_flushed | 0 |
| Innodb_buffer_pool_pages_free | 492 |
| Innodb_buffer_pool_pages_misc | 0 |
| Innodb_buffer_pool_pages_total | 512 |
| Innodb_buffer_pool_read_ahead_rnd | 1 |
| Innodb_buffer_pool_read_ahead_seq | 0 |
| Innodb_buffer_pool_read_requests | 135 |
| Innodb_buffer_pool_reads | 13 |
| Innodb_buffer_pool_wait_free | 0 |
| Innodb_buffer_pool_write_requests | 0 |
| Innodb_data_fsyncs | 3 |
| Innodb_data_pending_fsyncs | 0 |
| Innodb_data_pending_reads | 0 |
| Innodb_data_pending_writes | 0 |
| Innodb_data_read | 2510848 |
| Innodb_data_reads | 26 |
| Innodb_data_writes | 3 |
| Innodb_data_written | 1536 |
| Innodb_dblwr_pages_written | 0 |
| Innodb_dblwr_writes | 0 |
| Innodb_log_waits | 0 |
| Innodb_log_write_requests | 0 |
| Innodb_log_writes | 1 |
| Innodb_os_log_fsyncs | 3 |
| Innodb_os_log_pending_fsyncs | 0 |
| Innodb_os_log_pending_writes | 0 |
| Innodb_os_log_written | 512 |
| Innodb_page_size | 16384 |
| Innodb_pages_created | 0 |
| Innodb_pages_read | 20 |
| Innodb_pages_written | 0 |
| Innodb_row_lock_current_waits | 0 |
| Innodb_row_lock_time | 0 |
| Innodb_row_lock_time_avg | 0 |
| Innodb_row_lock_time_max | 0 |
| Innodb_row_lock_waits | 0 |
| Innodb_rows_deleted | 0 |
| Innodb_rows_inserted | 0 |
| Innodb_rows_read | 0 |
| Innodb_rows_updated | 0 |
| Key_blocks_not_flushed | 0 |
| Key_blocks_unused | 226896 |
| Key_blocks_used | 12952 |
| Key_read_requests | 206683288 |
| Key_reads | 191859 |
| Key_write_requests | 214773 |
| Key_writes | 104894 |
| Last_query_cost | 0.000000 |
| Max_used_connections | 200 |
| Ndb_cluster_node_id | 0 |
| Ndb_config_from_host | |
| Ndb_config_from_port | 0 |
| Ndb_number_of_data_nodes | 0 |
| Not_flushed_delayed_rows | 0 |
| Open_files | 489 |
| Open_streams | 0 |
| Open_tables | 256 |
| Opened_tables | 18937 |
| Prepared_stmt_count | 0 |
| Qcache_free_blocks | 1565 |
| Qcache_free_memory | 4547720 |
| Qcache_hits | 860770 |
| Qcache_inserts | 299052 |
| Qcache_lowmem_prunes | 75791 |
| Qcache_not_cached | 40669 |
| Qcache_queries_in_cache | 3828 |
| Qcache_total_blocks | 9896 |
| Questions | 2781187 |
| Rpl_status | NULL |
| Select_full_join | 7195 |
| Select_full_range_join | 0 |
| Select_range | 2366 |
| Select_range_check | 0 |
| Select_scan | 123291 |
| Slave_open_temp_tables | 0 |
| Slave_retried_transactions | 0 |
| Slave_running | OFF |
| Slow_launch_threads | 0 |
| Slow_queries | 5 |
| Sort_merge_passes | 57 |
| Sort_range | 23450 |
| Sort_rows | 4872396 |
| Sort_scan | 45272 |
| Ssl_accept_renegotiates | 0 |
| Ssl_accepts | 0 |
| Ssl_callback_cache_hits | 0 |
| Ssl_cipher | |
| Ssl_cipher_list | |
| Ssl_client_connects | 0 |
| Ssl_connect_renegotiates | 0 |
| Ssl_ctx_verify_depth | 0 |
| Ssl_ctx_verify_mode | 0 |
| Ssl_default_timeout | 0 |
| Ssl_finished_accepts | 0 |
| Ssl_finished_connects | 0 |
| Ssl_session_cache_hits | 0 |
| Ssl_session_cache_misses | 0 |
| Ssl_session_cache_mode | NONE |
| Ssl_session_cache_overflows | 0 |
| Ssl_session_cache_size | 0 |
| Ssl_session_cache_timeouts | 0 |
| Ssl_sessions_reused | 0 |
| Ssl_used_session_cache_entries | 0 |
| Ssl_verify_depth | 0 |
| Ssl_verify_mode | 0 |
| Ssl_version | |
| Table_locks_immediate | 747608 |
| Table_locks_waited | 1349 |
| Tc_log_max_pages_used | 0 |
| Tc_log_page_size | 0 |
| Tc_log_page_waits | 0 |
| Threads_cached | 7 |
| Threads_connected | 22 |
| Threads_created | 55958 |
| Threads_running | 2 |
| Uptime | 166654 |
±----------------------------------±-----------+
I think I should try to improve table_locking, but how?
I should also increase the key_buffer and table_cache which seems a bit low.
Any advice?
Sincerely,
py