解决OutOfMemoryError:|解决OutOfMemoryError: unable to create new native thread 解决OutOfMemoryError:unabletocreate

问题生产环境springboot工程卡死，检查日志发现了以下问题：

Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60000, active 0, maxActive 20 at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80) at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:84) at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:70) at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:336) at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84) at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324) at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) at com.github.pagehelper.PageInterceptor.intercept(PageInterceptor.java:143) at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61) at com.sun.proxy.$Proxy109.query(Unknown Source) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) ... 34 common frames omitted Caused by: com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60000, active 0, maxActive 20 at com.alibaba.druid.pool.DruidDataSource.getConnectionInternal(DruidDataSource.java:1265) at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:1086) at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:4544) at com.alibaba.druid.filter.stat.StatFilter.dataSource_getConnection(StatFilter.java:670) at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:4540) at com.alibaba.druid.filter.FilterAdapter.dataSource_getConnection(FilterAdapter.java:2723) at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:4540) at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1064) at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1056) at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:104) at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111) at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77) ... 46 common frames omitted Caused by: java.lang.OutOfMemoryError: unable to create new native thread at java.lang.Thread.start0(Native Method) at java.lang.Thread.start(Thread.java:717) at java.util.Timer.(Timer.java:176) at org.postgresql.util.SharedTimer.getTimer(SharedTimer.java:45) at org.postgresql.jdbc.PgConnection.getTimer(PgConnection.java:1165) at org.postgresql.jdbc.PgConnection.addTimerTask(PgConnection.java:1178) at org.postgresql.jdbc.PgStatement.startTimer(PgStatement.java:889) at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:429) at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:356) at org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:303) at org.postgresql.jdbc.PgStatement.executeCachedSql(PgStatement.java:289) at org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:266) at org.postgresql.jdbc.PgStatement.executeQuery(PgStatement.java:233) at com.alibaba.druid.pool.vendor.PGValidConnectionChecker.isValidConnection(PGValidConnectionChecker.java:65) at com.alibaba.druid.pool.DruidAbstractDataSource.validateConnection(DruidAbstractDataSource.java:1290) at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1535) at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2100)

分析原因可能的原因 OutOfMemoryError: unable to create new native thread出现的情况有两种：

服务器剩余内存不足（非JVM内存），不能创建新的线程
能创建的线程数的具体计算公式如下：

(MaxProcessMemory - JVMMemory - ReservedOsMemory) / (ThreadStackSize) = Number of threads

MaxProcessMemory指的是一个进程的最大内存 JVMMemoryJVM内存 ReservedOsMemory保留的操作系统内存 ThreadStackSize线程栈的大小

超出服务器用户最大进程限制:
通过以下命令可以查看（注意，不同用户，最大进程限制配置可能不一样）：

ulimit -u

解决OutOfMemoryError:|解决OutOfMemoryError: unable to create new native thread

文章图片
image.png 参考资料：
https://blog.csdn.net/thwsir/article/details/86480956
https://www.cnblogs.com/svennee/p/4331549.html
https://blog.csdn.net/qq171563857/article/details/94590992
分析通过检查jvm参数，发现没有设置-Xss，使用的默认大小，其次，使用free -m查看服务器可用内存，发现还有很多剩余，怀疑是超出服务器用户最大进程限制，由于需要先修复生产环境，没有过多时间分析定位错误，只保留了日志以及设置了用户的最大进程数，就重启了工程。
事后模拟

在java工程中定义一个http接口，当调用时，不停的创建和启动线程。

@GetMapping("/testThread") public void testThread() { List list = new ArrayList<>(); while(true) { Thread t = new Thread(() -> { try { Thread.sleep(600000L); } catch (InterruptedException e) { log.error("###",e); } }); t.start(); list.add(t); log.info(String.valueOf(list.size())); } }