使用HTTP-Kit驻留的线程

Question

我有几个线程在运行，每个线程都对HTTP工具包进行阻塞调用。我的代码一直在工作，但最近大约30分钟后就冻结了。我所有的线程都卡在以下一点上：

    sun.misc.Unsafe.park(Native Method)
    java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
    java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
    java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
    java.util.concurrent.CountDownLatch.await(CountDownLatch.java:231)
    clojure.core$promise$reify__7005.deref(core.clj:6823)
    clojure.core$deref.invokeStatic(core.clj:2228)
    clojure.core$deref.invoke(core.clj:2214)
    my_project.web$fetch.invokeStatic(web.clj:35)

(let [result @(org.httpkit.client/get "http://example.com")]

sun.security.ssl.SSLEngineImpl.readNetRecord(SSLEngineImpl.java:850)
sun.security.ssl.SSLEngineImpl.unwrap(SSLEngineImpl.java:781)
javax.net.ssl.SSLEngine.unwrap(SSLEngine.java:624)
org.httpkit.client.HttpsRequest.unwrapRead(HttpsRequest.java:35)
org.httpkit.client.HttpClient.doRead(HttpClient.java:131)
org.httpkit.client.HttpClient.run(HttpClient.java:377)
java.lang.Thread.run(Thread.java:748)

Answer 1

常见的做法是设置DefaultunCaughtExceptionHandler。如果线程中存在异常，这至少会给您一个指示。

(defn init-jvm-uncaught-exception-logging []
  (Thread/setDefaultUncaughtExceptionHandler
    (reify Thread$UncaughtExceptionHandler
      (uncaughtException [_ thread ex]
        (log/error ex "Uncaught exception on" (.getName thread))))))

Stuart Sierra写得很好：https://stuartsierra.com/2015/05/27/clojure-uncattle-exceptions