java - 好的http3 : unable to create new native thread

Question

遇到一个奇怪的问题，经过一番尝试后无法重现。如何重现它以及为什么会发生？

这是一个非并发任务，循环调用HTTP连接。

    public static Response syncGet(URL url) throws IOException {
        log.debug("http url:{}", url);
        OkHttpClient client = new OkHttpClient().newBuilder().connectTimeout(15L, TimeUnit.SECONDS)
                .readTimeout(30L, TimeUnit.SECONDS).build();

        Request request = new Request.Builder().url(url).get().addHeader("cache-control", "no-cache").build();
        Call call = client.newCall(request);
        return call.execute();
    }

堆栈:

    2019-12-05 11:20:56.068 ERROR 18484 --- [   scheduling-1] o.s.s.s.TaskUtils$LoggingErrorHandler    : Unexpected error occurred in scheduled task    java.lang.OutOfMemoryError: unable to create new native thread        at java.lang.Thread.start0(Native Method) [na:1.8.0_181]        at java.lang.Thread.start(Thread.java:717) [na:1.8.0_181]        at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:957) [na:1.8.0_181]        at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1378) [na:1.8.0_181]        at okhttp3.ConnectionPool.put(ConnectionPool.java:153) ~[okhttp-3.12.1.jar:na]        at okhttp3.OkHttpClient$1.put(OkHttpClient.java:167) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:266) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:135) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:114) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:126) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147) ~[okhttp-3.12.1.jar:na]        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121) ~[okhttp-3.12.1.jar:na]        at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:254) ~[okhttp-3.12.1.jar:na]        at okhttp3.RealCall.execute(RealCall.java:92) ~[okhttp-3.12.1.jar:na]        at chances.cms.util.HttpUtil.syncGet(HttpUtil.java:67) ~[classes/:na]        at chances.cms.task.CheckTask.checkContent(CheckTask.java:76) ~[classes/:na]        at chances.cms.task.CheckTask.check(CheckTask.java:60) ~[classes/:na]        at chances.cms.task.CheckTask.check(CheckTask.java:51) ~[classes/:na]        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]        at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]        at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]        at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93) [spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_181]        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_181]        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_181]        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_181]        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_181]        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_181]        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]

Answer 1

OkHttpClients should be shared

OkHttp performs best when you create a single OkHttpClient instance and reuse it for all of your HTTP calls. This is because each client holds its own connection pool and thread pools. Reusing connections and threads reduces latency and saves memory.

more detail: https://square.github.io/okhttp/3.x/okhttp/okhttp3/OkHttpClient.html

因此在 syncGet 方法之外创建 client 应该可以解决您的问题。