[HTTPCLIENT-1657] "Connection is not open" in httpClient.execute

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 4.4.1
• Assignee: Unassigned
• Reporter: Neil Newman
• Created: 09/Jun/15 22:35
• Updated: 04/May/17 09:48
• Resolved: 13/Jun/15 15:07

Description

I have a program that needs to solve several problems. For each problem, it can try several different algorithms in parallel. As soon as one algorithm solves the problem, I would like the others to terminate promptly. Some algorithms are accessed via HTTP requests: you make a POST with the problem to a server, block, and the server returns an answer. If another thread finds the answer before the server returns, I would like that thread to cancel the http request.

My code looks as follows

Example.java

// fields
        private final Lock lock;
        private final AtomicBoolean activeSolve;
        private HttpPost post;
        private final CloseableHttpClient httpClient = HttpClients.createDefault();


public String makePost() {
    post = new HttpPost("some url");
    final StringEntity stringEntity = new StringEntity("some json string", ContentType.APPLICATION_JSON);
    post.setEntity(stringEntity);
    try {
        lock.lock();
        activeSolve.set(true);
        lock.unlock();
        try (final CloseableHttpResponse httpResponse = httpClient.execute(post)) {
            final String response = EntityUtils.toString(httpResponse.getEntity());
            return response;
        }
    } catch (IOException e) {
        if (post.isAborted()) {
            log.trace("Web request was aborted");
            return "aborted";
        } else {
            throw new RuntimeException("Could not contact server", e);
        }
    } finally {
        lock.lock();
        activeSolve.set(false);
        lock.unlock();
    }
}

   public void interrupt() {
        lock.lock();
        if (activeSolve.get()) {
            post.abort();
        }
        lock.unlock();
    }

Every ~1000 problems or so, I'll see the following stacktrace:
java.lang.IllegalStateException: Connection is not open
at org.apache.http.util.Asserts.check(Asserts.java:34)
at org.apache.http.impl.BHttpConnectionBase.ensureOpen(BHttpConnectionBase.java:132)
at org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseEntity(DefaultBHttpClientConnection.java:177)
at org.apache.http.impl.conn.CPoolProxy.receiveResponseEntity(CPoolProxy.java:172)
at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:274)
at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:124)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:271)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)
at ... my classes

If I comment out the interrupt code and disable interrupting, I stop seeing this error.

Am I using the library incorrectly? I can't figure out what circumstances cause this to occur.

Issue Links

• is depended upon by: HADOOP-13973 S3A GET/HEAD requests failing: java.lang.IllegalStateException: Connection is not open/Connection pool shut down