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java - 谷歌应用引擎错误 : Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager

转载 作者：塔克拉玛干 更新时间：2023-11-03 03:01:32 36 4
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App Engine 给出错误:

com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager

当我在异步 Servlet 的 Callable 中调用 Google Vision API 时。如何让它发挥作用？

服务小程序:

public class OcrForTextServlet extends HttpServlet {
    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse response) {
            byte[] file = extractFile(req);
            String[] languages = req.getParameterValues("language");
            ExecutorService executor = Executors.newFixedThreadPool(2);
            Future<String> result = executor.submit(new OcrCallableTask(file, languages));
            executor.shutdown();
            response.getWriter().write(result.get()); //ERROR HERE

完整堆栈跟踪:

[INFO] java.util.concurrent.ExecutionException: com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager
[INFO]  at java.util.concurrent.FutureTask.report(FutureTask.java:122)
[INFO]  at java.util.concurrent.FutureTask.get(FutureTask.java:192)
[INFO]  at ocrme_backend.servlets.ocr.OcrForTextServlet.doPost(OcrForTextServlet.java:49)
[INFO]  at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
[INFO]  at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
[INFO]  at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:848)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1772)
[INFO]  at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:134)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:48)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.appengine.tools.development.jetty9.StaticFileFilter.doFilter(StaticFileFilter.java:122)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
[INFO]  at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
[INFO]  at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
[INFO]  at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1751)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:582)
[INFO]  at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
[INFO]  at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524)
[INFO]  at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
[INFO]  at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
[INFO]  at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
[INFO]  at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
[INFO]  at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
[INFO]  at com.google.appengine.tools.development.jetty9.DevAppEngineWebAppContext.doScope(DevAppEngineWebAppContext.java:112)
[INFO]  at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
[INFO]  at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
[INFO]  at com.google.appengine.tools.development.jetty9.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:596)
[INFO]  at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
[INFO]  at org.eclipse.jetty.server.Server.handle(Server.java:534)
[INFO]  at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320)
[INFO]  at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
[INFO]  at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283)
[INFO]  at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:108)
[INFO]  at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
[INFO]  at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
[INFO]  at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
[INFO]  at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
[INFO]  at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
[INFO]  at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
[INFO]  at java.lang.Thread.run(Thread.java:745)
[INFO] Caused by: com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager
[INFO]  at com.google.apphosting.api.ApiProxy$CallNotFoundException.foreignThread(ApiProxy.java:844)
[INFO]  at com.google.apphosting.api.ApiProxy.makeSyncCall(ApiProxy.java:116)
[INFO]  at com.google.appengine.api.urlfetch.URLFetchServiceImpl.fetch(URLFetchServiceImpl.java:40)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.fetchResponse(URLFetchServiceStreamHandler.java:543)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getInputStream(URLFetchServiceStreamHandler.java:422)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getResponseCode(URLFetchServiceStreamHandler.java:275)
[INFO]  at com.google.api.client.http.javanet.NetHttpResponse.<init>(NetHttpResponse.java:37)
[INFO]  at com.google.api.client.http.javanet.NetHttpRequest.execute(NetHttpRequest.java:94)
[INFO]  at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:972)
[INFO]  at com.google.api.client.auth.oauth2.TokenRequest.executeUnparsed(TokenRequest.java:283)
[INFO]  at com.google.api.client.auth.oauth2.TokenRequest.execute(TokenRequest.java:307)
[INFO]  at com.google.api.client.auth.oauth2.Credential.executeRefreshToken(Credential.java:570)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:362)
[INFO]  at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.fromStreamUser(GoogleCredential.java:772)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.fromStream(GoogleCredential.java:257)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.DefaultCredentialProvider.getCredentialUsingWellKnownFile(DefaultCredentialProvider.java:249)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.DefaultCredentialProvider.getDefaultCredentialUnsynchronized(DefaultCredentialProvider.java:117)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.DefaultCredentialProvider.getDefaultCredential(DefaultCredentialProvider.java:91)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.getApplicationDefault(GoogleCredential.java:213)
[INFO]  at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.getApplicationDefault(GoogleCredential.java:191)
[INFO]  at ocrme_backend.ocr.OCRProcessorImpl.getVisionService(OCRProcessorImpl.java:40)
[INFO]  at ocrme_backend.ocr.OCRProcessorImpl.<init>(OCRProcessorImpl.java:32)
[INFO]  at ocrme_backend.servlets.ocr.OcrCallableTask.doStaff(OcrCallableTask.java:27)
[INFO]  at ocrme_backend.servlets.ocr.OcrCallableTask.call(OcrCallableTask.java:39)
[INFO]  at ocrme_backend.servlets.ocr.OcrCallableTask.call(OcrCallableTask.java:14)
[INFO]  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[INFO]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[INFO]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[INFO]  ... 1 more

API 调用出错:

/**
 * Connects to the Vision API using Application Default Credentials.
 */
public static Vision getVisionService() throws IOException, GeneralSecurityException {
    GoogleCredential credential =
            GoogleCredential.getApplicationDefault().createScoped(VisionScopes.all());
    com.google.api.client.json.JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
    return new Vision.Builder(GoogleNetHttpTransport.newTrustedTransport(), jsonFactory, credential)
            .setApplicationName(APPLICATION_NAME)
            .build();
}

我正在使用最新版本的 javax.servlet-api (3.1.0)、GAE (1.9.52) 和 Java 8。我需要从异步部分获取结果。我怎样才能做到这一点？感谢您的帮助。

更新:
我尝试按照错误消息中所述使用 com.google.appengine.api.ThreadManager 但它给出了相同的错误。这是我更新的 servlet:

@Override
public void doPost(HttpServletRequest req, HttpServletResponse response) {

    try {
        byte[] file = extractFile(req);
        String[] languages = req.getParameterValues("language");

        ThreadFactory factory = ThreadManager.currentRequestThreadFactory();
        ExecutorService service = Executors.newCachedThreadPool(factory);
        Future<String> result =
                service.submit(new OcrCallableTask(file, languages));
        response.getWriter().write(result.get()); //ERROR HERE

下一个测试通过 OK:

public class OcrCallableTaskTest {
    @Test
    public void testCall() throws Exception {
        ExecutorService service = Executors.newFixedThreadPool(2);
        Future<String> result = service.submit(new OcrCallableTask(FileProvider.getFile(), null));
        Assert.assertTrue(result.get() != null);
        Assert.assertTrue(result.get().length() > 0);
    }
}

更新 2:
(在请求的线程中回复提议的工作人员。)
真的，我的 servlet 不需要额外的线程。这只是修复错误的尝试。如果我不在我的应用程序中使用多线程，我会遇到同样的错误:

[INFO] com.google.api.gax.grpc.ApiException: io.grpc.StatusRuntimeException: UNAUTHENTICATED
[INFO]  at com.google.api.gax.grpc.ExceptionTransformingCallable$ExceptionTransformingFuture.onFailure(ExceptionTransformingCallable.java:108)
[INFO]  at com.google.api.core.ApiFutures$1.onFailure(ApiFutures.java:52)
[INFO]  at com.google.common.util.concurrent.Futures$6.run(Futures.java:1310)
[INFO]  at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:457)
[INFO]  at com.google.common.util.concurrent.ExecutionList.executeListener(ExecutionList.java:156)
[INFO]  at com.google.common.util.concurrent.ExecutionList.execute(ExecutionList.java:145)
[INFO]  at com.google.common.util.concurrent.AbstractFuture.setException(AbstractFuture.java:202)
[INFO]  at io.grpc.stub.ClientCalls$GrpcFuture.setException(ClientCalls.java:463)
[INFO]  at io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:439)
[INFO]  at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:428)
[INFO]  at io.grpc.internal.ClientCallImpl.access$100(ClientCallImpl.java:76)
[INFO]  at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.close(ClientCallImpl.java:514)
[INFO]  at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.access$700(ClientCallImpl.java:431)
[INFO]  at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:546)
[INFO]  at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:52)
[INFO]  at io.grpc.internal.SerializingExecutor$TaskRunner.run(SerializingExecutor.java:152)
[INFO]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[INFO]  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[INFO]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
[INFO]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
[INFO]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[INFO]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[INFO]  at java.lang.Thread.run(Thread.java:745)
[INFO] Caused by: io.grpc.StatusRuntimeException: UNAUTHENTICATED
[INFO]  at io.grpc.Status.asRuntimeException(Status.java:540)
[INFO]  ... 15 more
[INFO] Caused by: com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager
[INFO]  at com.google.apphosting.api.ApiProxy$CallNotFoundException.foreignThread(ApiProxy.java:844)
[INFO]  at com.google.apphosting.api.ApiProxy.makeSyncCall(ApiProxy.java:116)
[INFO]  at com.google.appengine.api.urlfetch.URLFetchServiceImpl.fetch(URLFetchServiceImpl.java:40)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.fetchResponse(URLFetchServiceStreamHandler.java:543)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getInputStream(URLFetchServiceStreamHandler.java:422)
[INFO]  at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getResponseCode(URLFetchServiceStreamHandler.java:275)
[INFO]  at com.google.api.client.http.javanet.NetHttpResponse.<init>(NetHttpResponse.java:37)
[INFO]  at com.google.api.client.http.javanet.NetHttpRequest.execute(NetHttpRequest.java:94)
[INFO]  at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:972)
[INFO]  at com.google.auth.oauth2.UserCredentials.refreshAccessToken(UserCredentials.java:207)
[INFO]  at com.google.auth.oauth2.OAuth2Credentials.refresh(OAuth2Credentials.java:149)
[INFO]  at com.google.auth.oauth2.OAuth2Credentials.getRequestMetadata(OAuth2Credentials.java:135)
[INFO]  at io.grpc.auth.GoogleAuthLibraryCallCredentials$1.run(GoogleAuthLibraryCallCredentials.java:110)
[INFO]  ... 7 more

servlet 代码 - 无多线程:

 @Override
    public void doPost(HttpServletRequest req, HttpServletResponse response) {
        try {
            byte[] file = extractFile(req);
            String[] languages = req.getParameterValues("language");

            OCRProcessor processor = new OCRProcessorImpl();
            String jsonResult;

            if (languages == null || languages.length <= 0) { 
                jsonResult = processor.ocrForText(file);

接下来的测试顺利通过:

@Test
public void doOCR() throws Exception {
    byte[] file = FileProvider.getImageFile().getFile();
    String result = ocrProcessor.ocrForText(file);
    assertNotNull(result);
    assertTrue(result.length() > 0);
}

它接缝(GAE + API 调用)与 Servlet 架构不兼容。谢谢你的任何建议。

最佳答案

异步？

也许我误解你了，但你的servlet似乎不是异步的:

    Future<String> result =
            service.submit(new OcrCallableTask(file, languages));
    response.getWriter().write(result.get()); //ERROR HERE

您的 servlet 线程将阻塞，直到此 url 提取完成，因为 Future#get() 将等待任务完成。

并且，正如您的堆栈跟踪所示，ApiProxy 还调用了 snyc 方法:

at com.google.apphosting.api.ApiProxy.makeSyncCall(ApiProxy.java:116)

建议

看来 Google App Engine 还是 not open sourced ，所以我可以给你一些可能的方向:

  • 从ApiProxy的文档来看，这个类可能会使用一些变量，比如ThreadLocal来存储数据，所以使用Executors创建新线程> 可能会混淆 App Engine；

    It also stores an Environment for each thread, which contains additional user-visible information about the request

  • 在您的情况下，我没有看到使用多线程的必要性，您可能想尝试使用请求线程获取信息；

  • 如果你确实需要异步调用，你可能需要使用后台线程，然后在调用结束时通知用户；

更多

我尝试运行您的示例，但您的 Vision 类无法编译。所以我写了另一个例子，here ，运行良好。

以下是sdk反编译的源码，出现异常:

    ApiProxy.Environment threadLocalEnvironment = (ApiProxy.Environment)environmentThreadLocal.get();
    if(threadLocalEnvironment != null) {
        return threadLocalEnvironment;
    } else {
        ApiProxy.EnvironmentFactory envFactory = getEnvironmentFactory();
        if(envFactory != null) {
            ApiProxy.Environment environment = envFactory.newEnvironment();
            environmentThreadLocal.set(environment);
            return environment;
        } else {
            return null;
        }
    }

在你的情况下，因为它无法获取环境工厂，所以它无法获取环境，从而导致你的异常。

说到为什么没有环境工厂，估计是你配置错了(你的war是用GAE的server跑的吗？如果是本地测试，那是必须的。)

关于java - 谷歌应用引擎错误 : Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44832036/

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塔克拉玛干
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