当聚合器 POM 将子模块引用为其父模块时，如果运行多线程，Sonar Maven 插件会挂起答案

【问题标题】：Sonar Maven Plugin hangs if running Multi-Threaded when an Aggregator POM references a Child Module as its Parent当聚合器 POM 将子模块引用为其父模块时，如果运行多线程，Sonar Maven 插件会挂起
【发布时间】：2018-09-27 16:48:02
【问题描述】：

问题陈述

我有一个聚合器 POM，它的父 POM 也是它的子模块之一。当我运行具有正常目标（例如mvn clean install -T 2）的多线程 Maven 构建时，它按预期工作：父模块首先构建，然后是聚合器。

但是，当运行 mvn sonar:sonar -T 2 时，构建会无限期挂起（来自 org.sonarsource.scanner.maven:sonar-maven-plugin:3.4.0.905）。

示例项目

布局：

sample/
  - parent/
    - pom.xml
  - pom.xml

聚合器 POM (sample/pom.xml)：

<?xml version="1.0"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>com.sample</groupId>
    <artifactId>parent</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <relativePath>parent/pom.xml</relativePath>
  </parent>
  <artifactId>aggregator</artifactId>
  <packaging>pom</packaging>
  <modules>
    <module>parent</module>
  </modules>
</project>

父 POM (sample/parent/pom.xml)：

<?xml version="1.0"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.sample</groupId>
  <artifactId>parent</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>pom</packaging>
  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.sonarsource.scanner.maven</groupId>
          <artifactId>sonar-maven-plugin</artifactId>
          <version>3.4.0.905</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

构建日志

正常的多线程构建按预期工作：mvn clean install -T 2

DANIJOH2-M-C5DB:deadlock-sample danijoh2$ mvn clean install -T 2
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] parent                                                             [pom]
[INFO] aggregator                                                         [pom]
[INFO] 
[INFO] Using the MultiThreadedBuilder implementation with a thread count of 2
[INFO] 
[INFO] -------------------------< com.sample:parent >--------------------------
[INFO] Building parent 1.0.0-SNAPSHOT                                     [1/2]
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ parent ---
[INFO] Deleting /Users/danijoh2/Desktop/deadlock-sample/parent/target
[INFO] 
[INFO] --- maven-install-plugin:2.4:install (default-install) @ parent ---
[INFO] Installing /Users/danijoh2/Desktop/deadlock-sample/parent/pom.xml to /Users/danijoh2/.m2/repository/com/sample/parent/1.0.0-SNAPSHOT/parent-1.0.0-SNAPSHOT.pom
[INFO] 
[INFO] -----------------------< com.sample:aggregator >------------------------
[INFO] Building aggregator 1.0.0-SNAPSHOT                                 [2/2]
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ aggregator ---
[INFO] 
[INFO] --- maven-install-plugin:2.4:install (default-install) @ aggregator ---
[INFO] Installing /Users/danijoh2/Desktop/deadlock-sample/pom.xml to /Users/danijoh2/.m2/repository/com/sample/aggregator/1.0.0-SNAPSHOT/aggregator-1.0.0-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] parent ............................................. SUCCESS [  0.805 s]
[INFO] aggregator 1.0.0-SNAPSHOT .......................... SUCCESS [  0.024 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.984 s (Wall Clock)
[INFO] Finished at: 2018-04-17T08:15:31-07:00
[INFO] ------------------------------------------------------------------------

但是在运行声纳目标时，它会无限期挂起：mvn sonar:sonar -T 2 （这也可以用mvn clean install sonar:sonar -T 2 复制，在这种情况下，它会在构建和安装两个项目后立即挂起）

DANIJOH2-M-C5DB:deadlock-sample danijoh2$ mvn sonar:sonar -T 2
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] parent                                                             [pom]
[INFO] aggregator                                                         [pom]
[INFO] 
[INFO] Using the MultiThreadedBuilder implementation with a thread count of 2
<process is now hung>

使用单个线程运行相同的构建工作正常：mvn sonar:sonar

DANIJOH2-M-C5DB:deadlock-sample danijoh2$ mvn sonar:sonar
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] parent                                                             [pom]
[INFO] aggregator                                                         [pom]
[INFO] 
[INFO] -----------------------< com.sample:aggregator >------------------------
[INFO] Building aggregator 1.0.0-SNAPSHOT                                 [1/2]
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- sonar-maven-plugin:3.4.0.905:sonar (default-cli) @ aggregator ---
...
[INFO] ANALYSIS SUCCESSFUL, you can browse http://localhost:9000/dashboard/index/com.sample:aggregator
[INFO] Note that you will be able to access the updated dashboard once the server has processed the submitted analysis report
[INFO] More about the report processing at http://localhost:9000/api/ce/task?id=AWLUPrWVbruNGPzM1Q9P
[INFO] Task total time: 11.792 s
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] parent ............................................. SKIPPED
[INFO] aggregator 1.0.0-SNAPSHOT .......................... SUCCESS [ 16.700 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 18.462 s
[INFO] Finished at: 2018-04-17T08:35:01-07:00
[INFO] ------------------------------------------------------------------------

挂起 Maven 进程的堆栈跟踪

2018-04-17 08:25:33
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.152-b16 mixed mode):

"Attach Listener" #11 daemon prio=9 os_prio=31 tid=0x00007fcf4d22e800 nid=0x2807 waiting on condition [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE
"Service Thread" #8 daemon prio=9 os_prio=31 tid=0x00007fcf4982c000 nid=0x3703 runnable [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE
"C1 CompilerThread2" #7 daemon prio=9 os_prio=31 tid=0x00007fcf4b03a800 nid=0x4503 waiting on condition [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" #6 daemon prio=9 os_prio=31 tid=0x00007fcf4b039800 nid=0x3403 waiting on condition [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #5 daemon prio=9 os_prio=31 tid=0x00007fcf49832000 nid=0x4703 waiting on condition [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fcf49817000 nid=0x3207 runnable [0x0000000000000000] 
  java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fcf4a809800 nid=0x5003 in Object.wait() [0x0000700004411000] java.lang.Thread.State: WAITING (on object monitor)
  at java.lang.Object.wait(Native Method)
    - waiting on <0x0000000782098a08> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
    - locked <0x0000000782098a08> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
  at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fcf4a807000 nid=0x2d03 in Object.wait() [0x000070000430e000] java.lang.Thread.State: WAITING (on object monitor)
  at java.lang.Object.wait(Native Method)
    - waiting on <0x0000000782098bc0> (a java.lang.ref.Reference$Lock)
  at java.lang.Object.wait(Object.java:502)
  at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
    - locked <0x0000000782098bc0> (a java.lang.ref.Reference$Lock)
  at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"main" #1 prio=5 os_prio=31 tid=0x00007fcf4a006000 nid=0x1a03 waiting on condition [0x0000700003cfb000] java.lang.Thread.State: WAITING (parking)
  at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x0000000781595778> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
  at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
  at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
  at java.util.concurrent.ExecutorCompletionService.take(ExecutorCompletionService.java:193)
  at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.multiThreadedProjectTaskSegmentBuild(MultiThreadedBuilder.java:140)
  at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.build(MultiThreadedBuilder.java:101)
  at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
  at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
  at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
  at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
  at org.apache.maven.cli.MavenCli.execute(MavenCli.java:956)
  at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:290)
  at org.apache.maven.cli.MavenCli.main(MavenCli.java:194)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
  at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
  at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
  at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)

"VM Thread" os_prio=31 tid=0x00007fcf4b01c000 nid=0x5203 runnable 
"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fcf4a00f000 nid=0x2007 runnable 
"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fcf49800800 nid=0x1f03 runnable 
"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fcf4a010000 nid=0x2a03 runnable 
"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fcf4a010800 nid=0x5303 runnable 
"VM Periodic Task Thread" os_prio=31 tid=0x00007fcf49810800 nid=0x4303 waiting on condition 
JNI global references: 229

机器详情

DANIJOH2-M-C5DB:deadlock-sample danijoh2$ mvn --version
Apache Maven 3.5.3 (3383c37e1f9e9b3bc3df5050c29c8aff9f295297; 2018-02-24T11:49:05-08:00)
Maven home: /Users/danijoh2/Work/maven-3.5.3
Java version: 1.8.0_152, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.13.4", arch: "x86_64", family: "mac"

总结

我在 Maven 3.0.5、3.2.3、3.3.9 中也看到了相同的行为。我还尝试了 sonar-maven-plugin 3.0 和 3.3.0.603，结果相同。

在我们的项目中，有大约 100 个模块，运行多线程将我们的构建时间从大约 30 分钟缩短到

在项目上运行clean install -T 2 后，将sonar:sonar 作为专用步骤运行。
设置独立作业以构建和发布父 POM，并在聚合器中指定发布版本。

我现在将采用第一种方法，但希望看到sonar:sonar 的目标能够在未来处理这种情况。

【问题讨论】：

标签： maven sonarqube sonarqube-scan

【解决方案1】：

我没有看到任何声纳插件挂起的证据。从堆栈跟踪来看，它看起来像 maven 挂起。我错过了什么吗？

当给定多个任务时，maven 中的多线程支持被破坏。请参阅此 P/R 和相关票证，以及有关多线程的其他错误票证：https://github.com/apache/maven/pull/125

老实说，我不希望它很快得到修复，如果有的话。考虑迁移到 Gradle。

【讨论】：

我猜担心的原因是其他目标不会导致 Maven 像这样挂起，例如“mvn clean install site site:stage -T 2”运行没有问题。但是一旦将 sonar:sonar 添加到命令中，即使是单独添加，它也会导致 Maven 挂起。我会仔细阅读那张票，但对我来说这似乎是一个不同的问题。
我在本地构建了 maven/pull/125 中的更改，但它并没有改变结果（只是堆栈跟踪中的行号增加了 1 行）。我将不得不更深入地研究那个 MultiThreadedBuilder 类，以了解它为什么停止执行任务。
好的。可能有助于检查 Maven 错误跟踪器中的其他错误。如果您发现涉及声纳插件的内容，请告诉我。该插件应该在多线程环境中运行良好。
感谢您的指点，我查看了但找不到任何匹配的内容。我创建了MNG-6398 来跟踪。我同意，通常 Sonar 目标在多线程环境中运行良好，但是当我将聚合器重构为最后而不是首先运行以捕获聚合报告时，我遇到了这个问题。一旦我删除了声纳：声纳或回到单线程它运行良好。
好的，还有一个更新 - 我将我的项目配置迁移回来，以便聚合器和父 POM 是同一个。现在，当我尝试运行“mvn clean install sonar:sonar -T 4”时，我看到目标问题被调用两次，如 MNG-5965 所述。最终由于安装插件两次将数据写入本地存储库而失败，而其他项目正在读取它，这总是发生，但在构建中的不同位置。在这种情况下，您在 maven/pull/125 中的补丁确实可以解决此问题。