Spring Boot Callable 异步接口服务端超时后是否会继续执行业务逻辑
Spring Boot juc About 5,283 wordsController 代码
使用了Callable
作为返回值,Spring Boot
会当作异步接口来处理。
@GetMapping("/timeout")
public Callable<String> timeout() {
System.out.println(LocalDateTime.now() + ": 准备超长处理, threadId: " + Thread.currentThread().getId());
return () -> {
System.out.println(LocalDateTime.now() + ": 超长处理中, threadId: " + Thread.currentThread().getId());
LockSupport.park();
System.out.println(LocalDateTime.now() + ": 继续执行, threadId: " + Thread.currentThread().getId());
return "timeout";
};
}
客户端请求
超时后客户端收到503
错误。
❯ curl -vv http://localhost:8081/timeout
* Trying 127.0.0.1:8081...
* Connected to localhost (127.0.0.1) port 8081 (#0)
> GET /timeout HTTP/1.1
> Host: localhost:8081
> User-Agent: curl/7.88.1
> Accept: */*
>
< HTTP/1.1 503
< Cache-Control: private
< Content-Type: text/html;charset=utf-8
< Content-Language: en
< Content-Length: 451
< Date: Fri, 14 Jul 2023 04:40:55 GMT
< Connection: close
<
* Closing connection 0
<!doctype html><html lang="en"><head><title>HTTP Status 503 – Service Unavailable</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 503 – Service Unavailable</h1></body></html>%
服务端日志
可以发现30
秒后,中断了sleep
,直接继续执行sleep
后代码。
没有休眠60
秒,直接被唤醒,执行后续代码。
2023-07-14T10:18:36.543868: 超长处理, threadId: 28
java.lang.InterruptedException: sleep interrupted
at java.base/java.lang.Thread.sleep(Native Method)
at TestController.lambda$timeout$0(AuthController.java:39)
at org.springframework.web.context.request.async.WebAsyncManager.lambda$startCallableProcessing$4(WebAsyncManager.java:337)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:829)
2023-07-14T10:19:07.341425: 继续执行, threadId: 51
2023-07-14 10:19:07.357 WARN 61586 --- [nio-8081-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.context.request.async.AsyncRequestTimeoutException]
原理
实际调用是走到WebAsyncManager
的startCallableProcessing
方法。
调用taskExecutor
的submit
,里面调用Callable
的call
方法运行run
方法体。
// org.springframework.web.context.request.async.WebAsyncManager#startCallableProcessing(org.springframework.web.context.request.async.WebAsyncTask<?>, java.lang.Object...)
public final class WebAsyncManager {
public void startCallableProcessing(final WebAsyncTask<?> webAsyncTask, Object... processingContext) throws Exception {
// ...
try {
Future<?> future = this.taskExecutor.submit(() -> {
Object result = null;
try {
result = callable.call();
}
catch (Throwable ex) {
result = ex;
}
});
}
catch (RejectedExecutionException ex) {
Object result = interceptorChain.applyPostProcess(this.asyncWebRequest, callable, ex);
setConcurrentResultAndDispatch(result);
throw ex;
}
}
}
FutureTask
的run
方法内会捕获Throwable
级别的异常,且不对外抛出。
所以Callable
的run
方法体内无法感知是否有异常发生。对于Callable
中的业务逻辑排查增加了难度。
// java.util.concurrent.FutureTask#run
public class FutureTask<V> implements RunnableFuture<V> {
public void run() {
if (state != NEW ||
!RUNNER.compareAndSet(this, null, Thread.currentThread()))
return;
try {
Callable<V> c = callable;
if (c != null && state == NEW) {
V result;
boolean ran;
try {
result = c.call();
ran = true;
} catch (Throwable ex) {
result = null;
ran = false;
setException(ex);
}
if (ran)
set(result);
}
} finally {
// ...
}
}
}
最后会调用FutureTask
的cancel(boolean mayInterruptIfRunning)
方法,且参数mayInterruptIfRunning
为true
,意味着会调用Thread
的interrupt
方法,唤醒可能有阻塞线程的操作。
// java.util.concurrent.FutureTask#cancel
public class FutureTask<V> implements RunnableFuture<V> {
public boolean cancel(boolean mayInterruptIfRunning) {
// ...
try { // in case call to interrupt throws exception
if (mayInterruptIfRunning) {
try {
Thread t = runner;
if (t != null)
t.interrupt();
} finally { // final state
STATE.setRelease(this, INTERRUPTED);
}
}
} finally {
finishCompletion();
}
return true;
}
}
Views: 711 · Posted: 2023-07-18
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