在 GAE 1.7.3 中使用 DeferredTasks 时 PermGen 空间不足

Question

我最近切换到了 Google App Engine Java SDK 1.7.3。从那时起，每次我将DeferredTasks 提交到任务队列时，我都会用完 PermGen 空间。

• 将应用部署到 App Engine 时不会发生这种情况。它只发生在本地。但它阻止了我的本地测试和失败的集成测试。

• 这发生在带有 Java 6 的 MacOSX 10.7.5

  $ java -version 
  java version "1.6.0_37"
  Java(TM) SE Runtime Environment (build 1.6.0_37-b06-434-11M3909)
  Java HotSpot(TM) 64-Bit Server VM (build 20.12-b01-434, mixed mode)
  

• 这是我在问题发生时看到的堆栈跟踪的一部分。

  INFO: Successfully processed ../target/projectName/WEB-INF/queue.xml
  Nov 1, 2012 3:04:00 PM com.google.appengine.api.taskqueue.dev.LocalTaskQueue init
  INFO: LocalTaskQueue is initialized
  Nov 1, 2012 3:04:01 PM org.quartz.simpl.SimpleThreadPool initialize
  INFO: Job execution threads will use class loader of thread: 1255545583@qtp-1458850232-0
  Nov 1, 2012 3:04:02 PM org.quartz.core.QuartzScheduler <init>
  INFO: Quartz Scheduler v.UNKNOWN.UNKNOWN.UNKNOWN created.
  Nov 1, 2012 3:04:02 PM org.quartz.simpl.RAMJobStore initialize
  INFO: RAMJobStore initialized.
  Nov 1, 2012 3:04:02 PM org.quartz.impl.StdSchedulerFactory instantiate
  INFO: Quartz scheduler 'DefaultQuartzScheduler' initialized from default resource file in Quartz package: 'quartz.properties'
  Nov 1, 2012 3:04:02 PM org.quartz.impl.StdSchedulerFactory instantiate
  INFO: Quartz scheduler version: UNKNOWN.UNKNOWN.UNKNOWN
  Nov 1, 2012 3:04:02 PM org.quartz.core.QuartzScheduler start
  INFO: Scheduler DefaultQuartzScheduler_$_NON_CLUSTERED started.
  Nov 1, 2012 3:04:02 PM com.google.appengine.api.taskqueue.dev.LocalTaskQueue start_
  INFO: Local task queue initialized with base url http://localhost:8083
  Exception in thread "DefaultQuartzScheduler_Worker-9" java.lang.OutOfMemoryError: PermGen space
          at java.lang.ClassLoader.defineClass1(Native Method)
          at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
          at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
          at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
          at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
          at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
          at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
          at java.security.AccessController.doPrivileged(Native Method)
          at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
          at com.google.appengine.tools.development.DevAppServerClassLoader.loadClass(DevAppServerClassLoader.java:92)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
          at com.google.appengine.api.urlfetch.URLFetchServicePb$URLFetchRequest.newBuilder(URLFetchServicePb.java:1902)
          at com.google.appengine.api.taskqueue.dev.UrlFetchJob.newFetchRequest(UrlFetchJob.java:152)
          at com.google.appengine.api.taskqueue.dev.UrlFetchJob.execute(UrlFetchJob.java:83)
          at org.quartz.core.JobRunShell.run(JobRunShell.java:203)
          at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520)
  Exception in thread "1255545583@qtp-1458850232-0" java.lang.OutOfMemoryError: PermGen space
  Exception in thread "Timer-6" java.lang.OutOfMemoryError: PermGen space
  Exception in thread "Timer-4" java.lang.OutOfMemoryError: PermGen space
  Exception in thread "Timer-2" java.lang.OutOfMemoryError: PermGen space
  Exception in thread "Timer-8" java.lang.OutOfMemoryError: PermGen space
  

有关触发问题的代码，请参见下文。 DeferredTask 有一个 memcache 引用，用于从 memcache 获取数据并可能将其删除。任务延迟 10 秒运行。

class Foo {
    private void enqueueTask() {
        queue.add(TaskOptions.Builder.withPayload(new Task()).countdownMillis(10 * 1000));
    }

    private static class Task implements DeferredTask {
        private static final MemcacheService memcache = MemcacheServiceFactory.getMemcacheService();
        private static final Logger log = Logger.getLogger(Task.class.getName());

        @Override
        public void run() {
            final String key = ...;

            if (memcache.contains(key)) {
                final Object value = memcache.get(key);

                if (some condition depending on value) {
                    memcache.delete(key);
                    memcache.increment(some other field, -1l);
                }
            } else {
                log.warning("error message");
            }
        }
    }
}

其他人可以复制吗？谢谢！

更新：我在 GAE 的 Google 代码页面上为此创建了 issue 8377。

Answer 1

此问题已在 2014 年 8 月 12 日的 1.9.6 AppEngine SDK 版本中得到解决。 MaxPermSize 只能在本地开发服务器上设置。