java jdk 随机数阻塞问题

背景：

Java 功能压测的时候,执行数据库sql缓慢分析报错，使用的Sharding-jdbc，进行了分库分表。高TPS访问时，遇到了瓶颈，

报错：

"http-bio-8088-exec-3762" - Thread t@188077

   java.lang.Thread.State: BLOCKED

    at sun.security.provider.NativePRNG$RandomIO.implNextBytes(NativePRNG.java:543)

    - waiting to lock <404ee8b2> (a java.lang.Object) owned by "http-bio-8088-exec-3552" t@187443

    at sun.security.provider.NativePRNG$RandomIO.access$400(NativePRNG.java:331)

    at sun.security.provider.NativePRNG.engineNextBytes(NativePRNG.java:220)

    at java.security.SecureRandom.nextBytes(SecureRandom.java:468)

    at java.util.UUID.randomUUID(UUID.java:145)

    at io.shardingsphere.core.event.ShardingEvent.<init>(ShardingEvent.java:32)

    at io.shardingsphere.core.event.executor.SQLExecutionEvent.<init>(SQLExecutionEvent.java:34)

    at io.shardingsphere.core.event.executor.DMLExecutionEvent.<init>(DMLExecutionEvent.java:34)

    at io.shardingsphere.core.event.executor.SQLExecutionEventFactory.createEvent(SQLExecutionEventFactory.java:51)

    at io.shardingsphere.core.executor.sql.execute.SQLExecuteCallback.execute0(SQLExecuteCallback.java:89)

    at io.shardingsphere.core.executor.sql.execute.SQLExecuteCallback.execute(SQLExecuteCallback.java:69)

    at io.shardingsphere.core.executor.ShardingExecuteEngine.syncGroupExecute(ShardingExecuteEngine.java:182)

    at io.shardingsphere.core.executor.ShardingExecuteEngine.groupExecute(ShardingExecuteEngine.java:158)

    at io.shardingsphere.core.executor.sql.execute.SQLExecuteTemplate.executeGroup(SQLExecuteTemplate.java:71)

    at io.shardingsphere.core.executor.sql.execute.SQLExecuteTemplate.executeGroup(SQLExecuteTemplate.java:54)

    at io.shardingsphere.shardingjdbc.executor.AbstractStatementExecutor.executeCallback(AbstractStatementExecutor.java:122)

    at io.shardingsphere.shardingjdbc.executor.PreparedStatementExecutor.execute(PreparedStatementExecutor.java:161)

    at io.shardingsphere.shardingjdbc.jdbc.core.statement.ShardingPreparedStatement.execute(ShardingPreparedStatement.java:139)

    at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)

    at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)

    at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)

    at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)

    at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)

    at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)

    at sun.reflect.GeneratedMethodAccessor501.invoke(Unknown Source)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:498)

    at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)

    at com.sun.proxy.$Proxy49.update(Unknown Source)

    at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:294)

    at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62)

    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)

    at com.sun.proxy.$Proxy79.updateByAgentNoAndTradeOrderNo(Unknown Source)

主要原因是底层 使用了java.util.UUID.randomUUID，其中sun.security.provider.NativePRNG$RandomIO.implNextBytes 获取随机数，上锁了，block.

目前解决方案：

在tomcat 配置中  -Djava.security.egd=file:/dev/./urandom

参考：https://www.cnblogs.com/softidea/p/9725156.html