最近项目中频繁出现 Lock wait timeout exceeded; try restarting transaction这个错误，把我们弄得痛苦不堪啊，为了解决问题，上网上找好多资料，终于把问题复现了。具体操作步骤如下（我使用的mysql工具是 navicat）：
第一步：开启sql命令页面
第二步：输入start transaction;开启一个事务
第三步：输入update语句 UPDATE TABLENAME set time=null where id=29163;（切记不要 提交（commit；））
第四步：书写测试类
public class StTest implements Runnable{
private static ApplicationContext applicationContext=null;
private static AtomicInteger a=new AtomicInteger(0);
static {
applicationContext=new ClassPathXmlApplicationContext("classpath:application.xml");
}
public static void main(String[] args) throws Exception {
ExecutorService executorService = Executors.newFixedThreadPool(10);
for (int i = 0; i <10 ; i++) {
executorService.execute(new aaaa());
}
if(!executorService.isTerminated()){
executorService.shutdown();
}
}
@Override
public void run() {
XXXService bean = applicationContext.getBean(XXXService.class);
XXXBeand xx= null;
try {
xx= bean.byId(254213);
} catch (Exception e) {
e.printStackTrace();
}
long aaa=System.currentTimeMillis();
for (int i = 0; i < 10; i++) {
try {
bean.update(xx);
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println(System.currentTimeMillis()-aaa);
}
}
运行程序并且运行下面3个sql查看结果
SELECT * FROM information_schema.INNODB_TRX;
select * from information_schema.innodb_lock_waits;
select * from information_schema.innodb_locks;
得到以下运行结果。我们发现有其他几个的 trx_state 状态是LOCK WAIT，得到我们要复现的结果
第五步：等待错误出现，在我们等待一段时间之后会发现程序报错
Caused by: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3491)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3423)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:995)
at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:493)
at sun.reflect.GeneratedMethodAccessor21.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:55)
at com.sun.proxy.$Proxy17.execute(Unknown Source)
at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:41)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:66)
at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:45)
at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:100)
at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:75)
at sun.reflect.GeneratedMethodAccessor35.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:59)
at com.sun.proxy.$Proxy15.update(Unknown Source)
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:148)
at sun.reflect.GeneratedMethodAccessor34.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:354)
... 20 more
从上面得到的结果，可以知道这个错误是在一个事务没有提交的时候，其他事务也操作相同对象导致的，那么找到了问题的原因，我们就可以针对这种情况进行修改了。
这是本次我遇到的错误，分享给大家一下，以避免程序中遇到这样的情况。