如何跟踪并防止在单独进程中运行的c3po中出现死锁？ [英] How to trace and prevent the deadlock appeared in c3po which is running in seperate processes?

问题描述

我有一个非常简单的计算，该计算产生字母矩阵，并找到矩阵中的所有单词。单词中的字母是相邻的单元格。

I have a very simple computation which produces letter matrices finds probably all the words in the matrix. The letters in the word are adjacent cells.

   for (int i = 0; i < 500; i++) {
        System.out.println(i);
        Matrix matrix = new Matrix(4);
        matrix.scanWordsRandomly(9);
        matrix.printMatrix();
        System.out.println(matrix.getSollSize());
        matrix.write_to_db();
    }

这是持久代码。

public void write_to_db() {
    Session session = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
        session.beginTransaction();
        Matrixtr onematrixtr = new Matrixtr();
        onematrixtr.setDimension(dimension);
        onematrixtr.setMatrixstr(this.toString());
        onematrixtr.setSolsize(getSollSize());
        session.save(onematrixtr);
        for (Map.Entry<Kelimetr, List<Cell>> sollution : sollutions.entrySet()) {
            Kelimetr kelimetr = sollution.getKey();
            List<Cell> solpath = sollution.getValue();
            Solstr onesol = new Solstr();
            onesol.setKelimetr(kelimetr);
            onesol.setMatrixtr(onematrixtr);
            onesol.setSoltext(solpath.toString().replace("[", "").replace("]", "").replace("true", "").replace("false", ""));
            session.save(onesol);
        }

        session.getTransaction().commit();
        session.close();

    }
    catch (HibernateException he) {
        System.out.println("DB Error : " + he.getMessage());
        session.close();
    } 
    catch (Exception ex) {
        System.out.println("General Error : " + ex.getMessage());
    }
}

这是休眠配置文件。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/kelimegame_db_dev?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=UTF-8</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password">!.Wlu9RrCA</property>
    <property name="hibernate.show_sql">false</property>
    <property name="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</property>
    <property name="hibernate.format_sql">false</property>
    <!-- Use the C3P0 connection pool provider -->
    <property name="hibernate.c3p0.acquire_increment">50</property>
    <property name="hibernate.c3p0.min_size">10</property>
    <property name="hibernate.c3p0.max_size">100</property>
    <property name="hibernate.c3p0.timeout">300</property>
    <property name="hibernate.c3p0.max_statements">5</property>
    <property name="hibernate.c3p0.idle_test_period">3000</property>
    <mapping resource="kelimegame/entity/Progress.hbm.xml"/>
    <mapping resource="kelimegame/entity/Solstr.hbm.xml"/>
    <mapping resource="kelimegame/entity/Kelimetr.hbm.xml"/>
    <mapping resource="kelimegame/entity/User.hbm.xml"/>
    <mapping resource="kelimegame/entity/Achievement.hbm.xml"/>
    <mapping resource="kelimegame/entity/Matrixtr.hbm.xml"/>
  </session-factory>
</hibernate-configuration>

找到所有可能的解决方案后，我使用休眠模式保留了矩阵和解决方案。我也在使用c3pO库。我没有产生任何线程。所有工作都以非常简单的迭代方式完成。但是我在单独的进程中运行jar。
从不同的终端执行此操作：

After finding all possible solutions I persist the matrix and the solutions using hibernate. I am also using c3pO library. I am not spawning any thread. All the work is being done in a very simple iterative way. But I am running the jar in separate processes. From different terminals I am executing this :

java -jar NewDB.jar

我遇到了如下僵局：

Apr 25, 2013 8:38:05 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@7f0c09f9 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
Apr 25, 2013 9:08:23 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@7f0c09f9 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@2933f261
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#1
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@116dd369
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#0
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@41529b6f
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#2
    Pending Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@165ab5ea
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@1d5d211d
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@4d2905fa
Pool thread stack traces:
    Thread[C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#1,5,main]
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:662)
    Thread[C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#0,5,main]
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:662)
    Thread[C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#2,5,main]
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:662)


Apr 25, 2013 9:41:29 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@7f0c09f9 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
Apr 25, 2013 9:55:18 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@7f0c09f9 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@5a337b7d
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#0
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@69f079ce
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#1
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@2accf9b8
            on thread: C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#2
    Pending Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@771eb4fb
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@fc07d6
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@2266731b
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@740f0341
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@59edbee
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@78e924
        com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@2123aba
        com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@7acd8a65
Pool thread stack traces:
    Thread[C3P0PooledConnectionPoolManager[identityToken->z8kfsx8uibeyqevbbapc|4045cf35]-HelperThread-#0,5,main]
        java.text.NumberFormat.getInstance(NumberFormat.java:769)
        java.text.NumberFormat.getInstance(NumberFormat.java:393)
        java.text.MessageFormat.subformat(MessageFormat.java:1262)
        java.text.MessageFormat.format(MessageFormat.java:860)
        java.text.Format.format(Format.java:157)
        java.text.MessageFormat.format(MessageFormat.java:836)
        com.mysql.jdbc.Messages.getString(Messages.java:106)
        com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2552)
        com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3002)
        com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2991)
        com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3532)
        com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:943)
        com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4113)
        com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1308)
        com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
        com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2176)
        com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2158)
        com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
        com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
        sun.reflect.GeneratedConstructorAccessor7.newInstance(Unknown Source)
        sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        java.lang.reflect.Constructor.newInstance(Constructor.java:525)
        com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
        com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
        com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
        com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
        com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:183)
        com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:172)
        com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:188)Killed
caglar@ubuntu:~/NetBeansProjects/NewDB/dist$ 

我的问题如下：

1. 由于我在
   个单独的进程中运行程序，c3po中是否会发生这种死锁？


2. 在这个
   进程中应该使用一个进程和多个线程吗？


3. 如何跟踪此死锁以了解其原因？有没有办法跟踪导致死锁的多个JVM？

推荐答案

这是一个有趣的方法。

this is an interesting one.

您已经发布了两个不同的APPARENT DEADLOCKS。第一个是由c3p0尝试关闭（）连接引起的，并且那些close（）操作未及时成功或失败并带有Exception异常。第二个APPARENT DEADLOCK显示连接获取方面的问题：c3p0正在尝试获取新的Connection，并且这些尝试都没有成功，也没有及时失败并带有Exception。冻结非常不同的事实这一事实表明，在您正在执行的操作或类似操作的压力下，dbms锁定可能是一个更普遍的问题。对数据库运行多个进程应该没问题，但是您需要保持对限制的认识。

you've published two distinct APPARENT DEADLOCKS. the first one is being caused by c3p0 attempting to close() Connections, and those close() operations are neither succeeding nor failing with an Exception in a timely manner. the second APPARENT DEADLOCK shows problems with Connection acquisition: c3p0 is attempting to acquire new Connections, and those attempts are neither succeeding nor failing with an Exception in a timely manner. the fact that very different operations are freezing suggests that it might be a more general problem with your dbms locking up under the stress of what you are doing or somesuch. it should be no problem to run multiple processes against your database, but you need to stay cognizant of limits.

关于配置，有一些有趣的事情：

there are a few interesting things about your configuration:

1）hibernate.c3p0.max_statements = 5是一个非常糟糕的主意，几乎在任何池上，尤其是在这么大的池上。您最多拥有100个连接，并且只允许在它们之间总共缓存5条语句。这可能会给池和DBMS造成压力，因为您将不断地翻阅PreparedStatements，并且语句缓存对此进行了大量记账。您可能希望每个连接5个缓存语句 ，但这不是您配置的内容。您已为池设置了全局最大值。也许尝试hibernate.c3p0.maxStatementsPerConnection = 5代替？或将max_statements设置为零以关闭语句缓存，至少直到您解决死锁为止。参见 http://www.mchange.com/projects/c3p0/#configuring_statement_pooling

1) hibernate.c3p0.max_statements=5 is a very bad idea, on almost any pool and particularly on pools this large. you've got up to 100 Connections, and you're only allowing a total of 5 Statements to be cached between all of them. this might stress both the pool and the DBMS, as you will constantly be churning through PreparedStatements and the statement cache does a lot of bookkeeping about that. you may have meant that to be 5 cached statements per connection, but that's not what you have configured. you have set a global maximum for your pool. maybe try hibernate.c3p0.maxStatementsPerConnection=5 instead? or set max_statements to zero to turn statement caching off, at least until you resolve your deadlock. see http://www.mchange.com/projects/c3p0/#configuring_statement_pooling

2）如果您在多个进程而不是多个线程中运行计算，您是否真的需要每个进程容纳50-100个连接？事情很可能只是冻结了，因为您在dbms上强调了太多未完成的Connections，因为您的多个进程中的每个进程都需要大量的资源密集型Connections。您在任何进程中不需要的连接数就可以比在该进程中同时运行的客户端线程数多。我将hibernate.c3p0.acquire_increment设置为可能的值，并且可能将hibernate.c3p0.max_size设置为更小的值。

2) if you are running your computation in multiple processes rather than multiple Threads, do you really need each process to hold 50 - 100 Connections? things may well be freezing up simply because you are stressing the dbms with too many Connections outstanding as each of your multiple processes acquire lots of resource-heavy Connections. you don't need more Connections in any process than you might have client Threads running concurrently within that process. i'd set hibernate.c3p0.acquire_increment and probably hibernate.c3p0.max_size to much smaller values.

3）如果确实需要同时运行所有这些连接，则通过将config参数numHelperThreads增加到大于其默认值3的某个值，可以减少池陷入死锁的脆弱性。您可能希望numHelperThreads成为计算机上可用内核数量的两倍。考虑到您正在运行多个进程，您可能会发现自己已经饱和了CPU，这冻结了一切。因此，请注意这一点。

3) if you really do need all those Connections running simultaneously, you can reduce the vulnerability of your pools to deadlock by increasing the config parameter numHelperThreads to some value greater than its default of 3. you probably want numHelperThreads to be something like twice the number of cores available on your machine. given that you are running multiple processes though, you might find that you are saturating your CPU, and that is freezing things up. so watch for that.

基本上，请尝试更新配置，以便尽可能高效地使用资源-文件句柄，网络连接，CPU-

basically, try updating your configuration so that you are using resources -- file handles, network connections, CPU -- as efficiently as possible and so that you are not unnecessarily stressing the pool / statement cache / dbms more than you need to be.

如果这些建议不能解决问题，请发布以下内容的填充配置：你的游泳池。 c3p0在池初始化时将其配置转储到INFO级别。

if these suggestions don't resolve the problem, please post the fill config of your pools. c3p0 dumps its config at INFO level on pool initialization.

祝你好运！

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