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JDK1.8下多线程使用JDBC加载ClickHouse和hive驱动问题

article 2025/3/11 9:09:14

JDK1.8下多线程使用JDBC加载CH和hive驱动问题

文章目录

    • JDK1.8下多线程使用JDBC加载CH和hive驱动问题
      • 现象重现
      • DriverManager加载驱动过程
      • 分析猜想
      • 实验1
      • 实验2
      • 实验3
      • 小结
      • 解决方案
      • JVM深度分析

在线程池里并行加载ClickHouse和Hive驱动时，发现程序无反应。通过日志发现均卡在驱动加载部分。猜测加载驱动时发生问题。随即通过下方程序进行验证调试。

现象重现

public class DriverLock {
    public static void main(String[] args) {
        InnerCHThread chThread = new InnerCHThread();
        chThread.setName("chThread");
        InnerHiveThread hiveThread = new InnerHiveThread();
        hiveThread.setName("hiveThread");
        chThread.start();
        hiveThread.start();
    }

    public static class InnerCHThread extends Thread {
        @Override
        public void run() {
            try {
                Class.forName("com.clickhouse.jdbc.ClickHouseDriver", true, this.getClass().getClassLoader());
                System.out.println("com.clickhouse.jdbc.ClickHouseDriver");
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

    public static class InnerHiveThread extends Thread {
        @Override
        public void run() {
            try {
                Class.forName("org.apache.hive.jdbc.HiveDriver", true, this.getClass().getClassLoader());
                System.out.println("org.apache.hive.jdbc.HiveDriver");
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
}

线程dump

jstack命令

PS E:\code\myself\china-unicorn> jstack 13100
2023-03-29 14:40:17
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.333-b02 mixed mode):

"DestroyJavaVM" #13 prio=5 os_prio=0 tid=0x000001c2329d9000 nid=0x3eb0 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"hiveThread" #12 prio=5 os_prio=0 tid=0x000001c24f7b2000 nid=0x23a4 in Object.wait() [0x00000001016fd000]
   java.lang.Thread.State: RUNNABLE
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
        at java.lang.Class.newInstance(Class.java:442)
        at java.util.ServiceLoader$LazyIterator.nextService(ServiceLoader.java:380)
        at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:404)
        at java.util.ServiceLoader$1.next(ServiceLoader.java:480)
        at java.sql.DriverManager$2.run(DriverManager.java:603)
        at java.sql.DriverManager$2.run(DriverManager.java:583)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.sql.DriverManager.loadInitialDrivers(DriverManager.java:583)
        at java.sql.DriverManager.<clinit>(DriverManager.java:101)
        at org.apache.hive.jdbc.HiveDriver.<clinit>(HiveDriver.java:44)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:348)
        at com.donny.bigdata.surveillance.common.DriverLock$InnerHiveThread.run(DriverLock.java:35)

"chThread" #11 prio=5 os_prio=0 tid=0x000001c24f7b1800 nid=0x39e8 in Object.wait() [0x00000001015fe000]
   java.lang.Thread.State: RUNNABLE
        at com.clickhouse.jdbc.ClickHouseDriver.<clinit>(ClickHouseDriver.java:70)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:348)
        at com.donny.bigdata.surveillance.common.DriverLock$InnerCHThread.run(DriverLock.java:23)

"Service Thread" #10 daemon prio=9 os_prio=0 tid=0x000001c24f64e000 nid=0x2e68 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread2" #9 daemon prio=9 os_prio=2 tid=0x000001c24f637000 nid=0x316c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #8 daemon prio=9 os_prio=2 tid=0x000001c24f5de000 nid=0x5b08 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #7 daemon prio=9 os_prio=2 tid=0x000001c24f5db000 nid=0x4c60 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Monitor Ctrl-Break" #6 daemon prio=5 os_prio=0 tid=0x000001c24f5a6000 nid=0x4474 runnable [0x0000000100ffe000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
        at java.net.SocketInputStream.read(SocketInputStream.java:171)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
        - locked <0x000000076bc2fa10> (a java.io.InputStreamReader)
        at java.io.InputStreamReader.read(InputStreamReader.java:184)
        at java.io.BufferedReader.fill(BufferedReader.java:161)
        at java.io.BufferedReader.readLine(BufferedReader.java:324)
        - locked <0x000000076bc2fa10> (a java.io.InputStreamReader)
        at java.io.BufferedReader.readLine(BufferedReader.java:389)
        at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:49)

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x000001c24ddb5000 nid=0x3774 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x000001c24dd5f000 nid=0x41d4 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x000001c24d61c800 nid=0x3430 in Object.wait() [0x0000000100cff000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x000000076b388ee8> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:150)
        - locked <0x000000076b388ee8> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:171)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=2 tid=0x000001c24dd46800 nid=0x3f8c in Object.wait() [0x0000000100bff000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x000000076b386c00> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x000000076b386c00> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=2 tid=0x000001c24dd20800 nid=0x3b50 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x000001c2329ee000 nid=0x414 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x000001c2329ef800 nid=0x33d0 runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x000001c2329f1000 nid=0x54a4 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x000001c2329f3000 nid=0x4ea8 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x000001c24f7af000 nid=0x5720 waiting on condition

JNI global references: 315

jstack -m 命令

PS E:\code\myself\china-unicorn> jstack -m 13100
Attaching to process ID 13100, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.333-b02
Deadlock Detection:

No deadlocks found.

----------------- 0 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 1 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 2 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 3 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 4 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 5 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 6 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 7 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 8 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 9 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 10 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
0x000001c24dd60080              ????????
----------------- 11 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 12 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
0x3659be07190c00c6              ????????
----------------- 13 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
0x0065006800630061              ????????
----------------- 14 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 15 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 16 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 17 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14
----------------- 18 -----------------
0x00007ffafbdaaa24      ntdll!NtWaitForSingleObject + 0x14

通过dump文件没有发下明显的死锁。

转而查询运行中的线程，驱动类HiveDriver和ClickHouseDriver都通过java.sql.DriverManager.registerDriver方法进行注册的，都借助了类DriverManager。

DriverManager加载驱动过程

DriverManager是JDK提供的一个驱动管理类。对其加载驱动时的过程分析。DriverManager初始化的时候会先加载loadInitialDrivers方法。

static {
    loadInitialDrivers();
    println("JDBC DriverManager initialized");
}

在loadInitialDrivers方法中会通过类ServiceLoader来获取实现了Driver接口的驱动类(会扫描classpath下的满足要求的驱动类)

    private static void loadInitialDrivers() {
        String drivers;
        try {
            drivers = AccessController.doPrivileged(new PrivilegedAction<String>() {
                public String run() {
                    return System.getProperty("jdbc.drivers");
                }
            });
        } catch (Exception ex) {
            drivers = null;
        }

        AccessController.doPrivileged(new PrivilegedAction<Void>() {
            public Void run() {

                ServiceLoader<Driver> loadedDrivers = ServiceLoader.load(Driver.class);
                Iterator<Driver> driversIterator = loadedDrivers.iterator();

                try{
                    // 当线程hiveThread执行完对hive驱动类的加载之后，迭代器中也加入了ch的驱动类
                    while(driversIterator.hasNext()) {
                        driversIterator.next();
                    }
                } catch(Throwable t) {
                // Do nothing
                }
                return null;
            }
        });

        println("DriverManager.initialize: jdbc.drivers = " + drivers);
        // 一般逻辑（系统属性jdbc.drivers为空），直接跳出了。
        if (drivers == null || drivers.equals("")) {
            return;
        }
        // 有jdbc.drivers环境配置的时候，会一次尝试对jdbc.drivers中的服务类进行类加载
        String[] driversList = drivers.split(":");
        println("number of Drivers:" + driversList.length);
        
        for (String aDriver : driversList) {
            try {
                println("DriverManager.Initialize: loading " + aDriver);
                Class.forName(aDriver, true,
                        ClassLoader.getSystemClassLoader());
            } catch (Exception ex) {
                println("DriverManager.Initialize: load failed: " + ex);
            }
        }
    }

在ServiceLoader中两个对象providers，lookupIterator和方法iterator()，providers是已经完成加载的驱动服务类集合对象，lookupIterator等待加载的驱动服务类集合的迭代器对象。

// 已经完成加载的驱动服务类集合对象
private LinkedHashMap<String,S> providers = new LinkedHashMap<>();
// 等待加载的驱动服务类集合的迭代器对象
private LazyIterator lookupIterator;

public Iterator<S> iterator() {
        return new Iterator<S>() {

            Iterator<Map.Entry<String,S>> knownProviders
                = providers.entrySet().iterator();

            public boolean hasNext() {
                // 直接跳过已加载的驱动服务类
                if (knownProviders.hasNext())
                    return true;
                return lookupIterator.hasNext();
            }

            public S next() {
                // 优先遍历已加载的驱动服务类
                if (knownProviders.hasNext())
                    return knownProviders.next().getValue();
                return lookupIterator.next();
            }

            public void remove() {
                throw new UnsupportedOperationException();
            }

        };
    }

LazyIterator中有重要方法 hasNextService被driversIterator.hasNext()调用，nextService被 driversIterator.next()调用

        private boolean hasNextService() {
            // 下一个服务的名不为空，说明还有服务
            if (nextName != null) {
                return true;
            }
            if (configs == null) {
                try {
                    String fullName = PREFIX + service.getName();
                    if (loader == null)
                        configs = ClassLoader.getSystemResources(fullName);
                    else
                        configs = loader.getResources(fullName);
                } catch (IOException x) {
                    fail(service, "Error locating configuration files", x);
                }
            }
            while ((pending == null) || !pending.hasNext()) {
                if (!configs.hasMoreElements()) {
                    return false;
                }
                pending = parse(service, configs.nextElement());
            }
            nextName = pending.next();
            return true;
        }
        
        private S nextService() {
            if (!hasNextService())
                throw new NoSuchElementException();
            String cn = nextName;
            nextName = null;
            Class<?> c = null;
            try {
                c = Class.forName(cn, false, loader);
            } catch (ClassNotFoundException x) {
                fail(service,
                     "Provider " + cn + " not found");
            }
            if (!service.isAssignableFrom(c)) {
                fail(service,
                     "Provider " + cn  + " not a subtype");
            }
            try {
                // 卡住的方法
                // 对驱动类的实例创建（驱动类的加载）
                S p = service.cast(c.newInstance());
                providers.put(cn, p);
                return p;
            } catch (Throwable x) {
                fail(service,
                     "Provider " + cn + " could not be instantiated",
                     x);
            }
            throw new Error();          // This cannot happen
        }

分析猜想

当chThread和hiveThread分别去加载驱动服务的时候，当hiveThread线程执行到实例化CH驱动服务类的时候正好与chThread线程实例化CH驱动服务类，形成了竞争关系，造成了死锁。

实验1

引入多个jar，只指明一个驱动服务类进行主动加载

import java.sql.Driver;
import java.sql.DriverManager;

/**
 * 多线程的场景下DriverManager注册驱动死锁
 *
 * @author 1792998761@qq.com
 * @date 2023/3/29 10:55
 */
public class DriverLock {
    public static void main(String[] args) {

        try {
            Class.forName("org.apache.hive.jdbc.HiveDriver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        java.util.Enumeration<Driver> drivers = DriverManager.getDrivers();
        while (drivers.hasMoreElements()) {
            System.out.println(drivers.nextElement().toString());
        }
    }

}

结果

com.clickhouse.jdbc.ClickHouseDriver@15975490
org.apache.derby.jdbc.AutoloadedDriver40@7c16905e
org.apache.hive.jdbc.HiveDriver@3e6fa38a

实验2

引入多个jar，不指明驱动服务类进行主动加载，只主动调用DriverManager.getDrivers()

import java.sql.Driver;
import java.sql.DriverManager;

/**
 * 多线程的场景下DriverManager注册驱动死锁
 *
 * @author 1792998761@qq.com
 * @date 2023/3/29 10:55
 */
public class DriverLock {
    public static void main(String[] args) {
        java.util.Enumeration<Driver> drivers = DriverManager.getDrivers();
        while (drivers.hasMoreElements()) {
            System.out.println(drivers.nextElement().toString());
        }
    }
}

结果

org.apache.hive.jdbc.HiveDriver@763d9750
com.clickhouse.jdbc.ClickHouseDriver@6b143ee9
org.apache.derby.jdbc.AutoloadedDriver40@2a2d45ba

实验3

多线程下，调用DriverManager.getDrivers()

package com.donny.bigdata.surveillance.common;

import java.sql.Driver;
import java.sql.DriverManager;

/**
 * 多线程的场景下DriverManager注册驱动死锁
 *
 * @author 1792998761@qq.com
 * @date 2023/3/29 10:55
 */
public class DriverLock {
    public static void main(String[] args) {
        InnerCHThread chThread = new InnerCHThread();
        chThread.setName("chThread");
        InnerHiveThread hiveThread = new InnerHiveThread();
        hiveThread.setName("hiveThread");
        chThread.start();
        hiveThread.start();
    }

    public static class InnerCHThread extends Thread {
        @Override
        public void run() {
            try {
                java.util.Enumeration<Driver> drivers = DriverManager.getDrivers();
                while (drivers.hasMoreElements()) {
                    System.out.println(drivers.nextElement().toString());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public static class InnerHiveThread extends Thread {
        @Override
        public void run() {
            try {
                java.util.Enumeration<Driver> drivers = DriverManager.getDrivers();
                while (drivers.hasMoreElements()) {
                    System.out.println(drivers.nextElement().toString());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

结果

org.apache.hive.jdbc.HiveDriver@489c2bd0
com.clickhouse.jdbc.ClickHouseDriver@15fddb00
org.apache.derby.jdbc.AutoloadedDriver40@7c57eb6f
org.apache.hive.jdbc.HiveDriver@489c2bd0
com.clickhouse.jdbc.ClickHouseDriver@15fddb00
org.apache.derby.jdbc.AutoloadedDriver40@7c57eb6f

小结

  • DriverManager类在加载驱动服务类的时候，会扫描classpath下所有合适的类进行类加载。

  • 对于多线程中通过DriverManager类指明加载类很容易就造成死锁。

解决方案

  1. 在非多线程场景下使用DriverManager，提前进行服务类加载。

JVM深度分析

JDK的sql设计不合理导致的驱动类初始化死锁问题

加载多个JdbcDriver造成死锁


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