我正在使用 mysql 5.5.32。下面是我的配置文件（my.cnf）...
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
innodb_file_per_table=1
skip-name-resolve
innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
log-error=/var/log/mysql/mysql_error.log
long_query_time=1
slow_query_log=1
log-warnings=2
slow-query-log-file=/var/log/mysql/log-slow-queries.log
#starting
#old_passwords=1
#log-bin
#binlog-do-db=<database name> # input the database which should be replicated
#binlog-ignore-db=mysql # input the database that should be ignored for replication
#binlog-ignore-db=test
server-id=1
#ending
open_files_limit= 2000
thread_cache_size = 64
query_cache_limit=400M
query_cache_size = 400M
query_cache_type=1
[mysql.server]
user=mysql
basedir=/var/lib
[mysqld_safe]
#log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
当我重新启动 mysql 时，我很快就进入了 mysql 控制台。一段时间后，当我尝试进入 mysql 控制台时，大约需要 15-20 秒。
我使用命令show processlist来检查查询，但 mysql 服务器上没有负载。
为什么要花太多时间？如何跟踪错误是什么？