11

我在我的 Tomcat 日志中不断收到此异常：

com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1201fd18 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@408f3be4 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@7ba516d8 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
    Pending Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@137efe53
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@766b0524
Pool thread stack traces:
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

我将 Hibernate 3.6.2 和 C3P0 0.9.1.2 与 MySQL 一起使用。经过几个小时的谷歌搜索，这个明显的死锁异常似乎通常与准备好的语句缓存有关。这是我的 hibernate.cfg.xml 中的 C3P0 配置：

<propertyname="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.acquire_increment">5</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">60</property>
<property name="hibernate.c3p0.idle_test_period">120</property>
<property name="hibernate.c3p0.timeout">180</property>              
<property name="hibernate.c3p0.max_statements">0</property>

我没有做任何语句缓存。任何关于这里有什么问题的提示将不胜感激。

4

3 回答 3

11

解除锁定的任务是连接获取任务。也就是说，c3p0 正在尝试从您的数据库中获取新的连接，而这些连接获取尝试需要很长时间。

我要做的第一件事是升级到 0.9.2.1，它在获取尝试有时会失败的情况下执行一轮连接获取的方法有了很大改进。

如果这不能解决您的问题，那么您需要弄清楚为什么 c3p0 获取连接的尝试会长时间挂起：既没有成功也没有失败并出现异常。

于 2013-08-07T10:41:31.650 回答
1

在我非常特殊的情况下，问题与我部署应用程序的服务器的配置有关。

只有在打印出我的应用程序的堆栈跟踪后，它才被挂起，因为 oracle 驱动程序正在等待生成一个安全的随机数：

Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
  java.io.FileInputStream.readBytes(Native Method)
  java.io.FileInputStream.read(FileInputStream.java:255)
  sun.security.provider.SeedGenerator$URLSeedGenerator.getSeedBytes(SeedGenerator.java:539)
  sun.security.provider.SeedGenerator.generateSeed(SeedGenerator.java:144)
  sun.security.provider.SecureRandom$SeederHolder.(SecureRandom.java:203)
  sun.security.provider.SecureRandom.engineNextBytes(SecureRandom.java:221)
  java.security.SecureRandom.nextBytes(SecureRandom.java:468)
  oracle.security.o5logon.O5Logon.a(Unknown Source)
  oracle.security.o5logon.O5Logon.(Unknown Source)
  oracle.jdbc.driver.T4CTTIoauthenticate.(T4CTTIoauthenticate.java:582)
  oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:401)
  oracle.jdbc.driver.PhysicalConnection.(PhysicalConnection.java:553)
  oracle.jdbc.driver.T4CConnection.(T4CConnection.java:254)
  oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
  oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:528)
  com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
  com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
  com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
  com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
  com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
  com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
  com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
  com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

然后我必须学习和了解一点关于熵噪声的知识，并在我的 Unix 朋友的帮助下意识到其中一台服务器没有安装产生“噪声”的包。

如以下帖子所述，我运行了以下命令： cat /proc/sys/kernel/random/entropy_avail 23 cat /proc/sys/kernel/random/poolsize 4096

所以那里的熵太少，无法生成安全的随机数。

安装软件包 cat /proc/sys/kernel/random/entropy_avail 4096 之后，我没有更明显的死锁，我的应用程序可以连接到数据库。

http://www.usn-it.de/index.php/2009/02/20/oracle-11g-jdbc-driver-hangs-blocked-by-devrandom-entropy-pool-empty/

于 2016-01-06T17:19:16.370 回答
0

之前遇到过类似的错误。

它也可能是由数据库服务器阻止您的 IP 引起的。确保您的服务器的 IP 未被数据库服务器/云提供商阻止。

在我的情况下，试图通过多线程将数据插入云中的数据库，它只适用于本地，但不适用于服务器（在不同的网络上）。

于 2016-09-02T22:12:33.467 回答