StreamingSubscription - Error: Connection is still allocated

[avromf]

For the following code:

        WellKnownFolderName sd = WellKnownFolderName.Inbox;
        FolderId folderId = new FolderId(sd);

        List<FolderId> folder = new ArrayList<FolderId>();
        folder.add(folderId);

        StreamingSubscription subscription = service.subscribeToStreamingNotifications(folder, EventType.NewMail);
        StreamingSubscriptionConnection conn = new StreamingSubscriptionConnection(service, 30);
        conn.addSubscription(subscription);
        EventDelegate delegate = new EventDelegate(service);
        conn.addOnNotificationEvent(delegate);
        conn.addOnDisconnect(delegate);
        conn.open();
        EmailMessage msg = new EmailMessage(service);
        msg.setSubject("Testing Streaming Notification on " + new Date());
        msg.setBody(MessageBody.getMessageBodyFromText("Streaming Notification Test"));
        msg.getToRecipients().add("someone@somewhere.com");
        msg.send();

I get the following error:

 microsoft.exchange.webservices.data.exception.ServiceRequestException: The request failed. Connection is still allocated
 at microsoft.exchange.webservices.data.core.request.SimpleServiceRequestBase.internalExecute(SimpleServiceRequestBase.java:80)
 at microsoft.exchange.webservices.data.core.request.MultiResponseServiceRequest.execute(MultiResponseServiceRequest.java:160)
 at microsoft.exchange.webservices.data.core.ExchangeService.internalCreateItems(ExchangeService.java:592)
 at microsoft.exchange.webservices.data.core.ExchangeService.createItem(ExchangeService.java:651)
 at microsoft.exchange.webservices.data.core.service.item.Item.internalCreate(Item.java:247)
 at microsoft.exchange.webservices.data.core.service.item.EmailMessage.internalSend(EmailMessage.java:147)
 at microsoft.exchange.webservices.data.core.service.item.EmailMessage.send(EmailMessage.java:258)
 at test.TestEWS.main(TestEWS.java:287)
 Caused by: java.lang.IllegalStateException: Connection is still allocated
 at org.apache.http.util.Asserts.check(Asserts.java:34)
 at org.apache.http.impl.conn.BasicHttpClientConnectionManager.getConnection(BasicHttpClientConnectionManager.java:248)
 at org.apache.http.impl.conn.BasicHttpClientConnectionManager$1.get(BasicHttpClientConnectionManager.java:199)
 at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:173)
 at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
 at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86)
 at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
 at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
 at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
 at microsoft.exchange.webservices.data.core.request.HttpClientWebRequest.executeRequest(HttpClientWebRequest.java:291)
 at microsoft.exchange.webservices.data.core.request.ServiceRequestBase.getEwsHttpWebResponse(ServiceRequestBase.java:780)
 at microsoft.exchange.webservices.data.core.request.ServiceRequestBase.validateAndEmitRequest(ServiceRequestBase.java:719)
 at microsoft.exchange.webservices.data.core.request.SimpleServiceRequestBase.internalExecute(SimpleServiceRequestBase.java:68)
 ... 7 more

I should note that this used to work in the past.

Continuing with some tests on this, creating a separate ExchangeService object for sending the email works. However, the following code still does not work.

        StreamingSubscription subscription = service.subscribeToStreamingNotifications(folder, EventType.NewMail);
        StreamingSubscriptionConnection conn = new StreamingSubscriptionConnection(service, 30);
        conn.addSubscription(subscription);
        conn.open();
        subscription.unsubscribe();
        if (conn.getIsOpen())
            conn.close();

The line subscription.unsubscribe(); will still result in an "Connection is still allocated" error. Also, if I comment it out, the line conn.close(); hangs.

[vbauer]

Btw, maybe it will be better to use PoolingHttpClientConnectionManager instead of BasicHttpClientConnectionManager.

[MikeN123]

I think the implementation of any streaming requests is quite broken at the moment. We switched to a BasicHttpClientConnectionManager because the old implementation was leaking connections all over the place. I still think this change if fine, but for the streaming subs we need more than 1 connection, so it probably needs it's own connection manager (which would be a pooling one without any limits).

But another issue with the streaming subscriptions is the whole threading model. The current model (see HangingServiceRequestBase) simply spawns it's own thread pool, starts a thread (and then immediately shuts down the thread pool), and will call the callbacks whenever any data is received (and not fully cleanup after itself). I don't think all users are aware of the extra threads being created, which may cause all kinds of multi-threading bugs.

Wouldn't it be better to create some await() of select() call to wait for a response to one or more subscriptions? In that case the developers can choose to handle the multi-threading themselves.

[vbauer]

I've just dug a little bit in the networking part and.. it looks like it should be completely rewritten.

[fboucquez]

+1

What about using protected and factory methods like Spring does so devs can extend clases?

For example, instead of having

HttpClientConnectionManager httpConnectionManager = new BasicHttpClientConnectionManager(registry); in ExchangeServiceBase.initializeHttpClient

you can have a HttpClientConnectionManager httpConnectionManager = createHttpClientConnectionManager(registry); where createHttpClientConnectionManager is a protected method that we can override.

[ganeshgowtham]

I am basically struck at the same issue.

Unable to findItems(...) using the same service instance, I am getting "java.lang.IllegalStateException: Connection is still allocated".

Is there any work around (or) temporary fix for the same ?

[avromf]

@ganeshgowtham Make sure you are using the 2.0 release.

[ganeshgowtham]

I am using version 2.0 as said.

Still facing problem, it works when we have code in sync block.

Connection is leaking and though i have disconnect on service via listener

[kamaci]

I access to e-mails asynchronously but get the same error with version 2.0. I had to do that:

synchronized (this) { message = EmailMessage.bind(service, userItem.getId()); message.load(propertySet); }

However this breaks my async design. Any ideas?

[avromf]

@ganeshgowtham @kamaci Looking at what you both have said, you don't mention anywhere that you were trying to use streaming subscriptions. The original bug that I reported and later fixed was specifically for streaming subscriptions. If you are getting this error and are not using streaming subscriptions, then it maybe it is a separate issue.

[ganeshgowtham]

I am using streaming subscription to get calendar events.

Side note I have another query, for every calendar event creation I am getting atleast 7-8 notification events.

In chaos which one to consume and which one to discard.

-- Thanks Ganesh Gowtham

On 29-May-2017 10:18 PM, "Avrom" notifications@github.com wrote:

@ganeshgowtham https://github.com/ganeshgowtham @kamaci https://github.com/kamaci Looking at what you both have said, you don't mention anywhere that you were trying to use streaming subscriptions. The original bug that I reported and later fixed was specifically for streaming subscriptions. If you are getting this error and are not using streaming subscriptions, then it maybe it is a separate issue.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/OfficeDev/ews-java-api/issues/276#issuecomment-304699514, or mute the thread https://github.com/notifications/unsubscribe-auth/ADTVb18V3NJcvgOo2XxD8BzQFTyvR7O6ks5r-vbCgaJpZM4D4k18 .

[avromf]

@ganeshgowtham Do you have some sample code for testing this?

[kamaci]

@avromf I do not use streaming subscription. Is it a known bug that I should synchronize access to ExchangeService object?

[kamaci]

@avromf OK I see that it is not thread safe: https://msdn.microsoft.com/en-us/library/microsoft.exchange.webservices.data.exchangeservice(v=exchg.80).aspx

[alexmreis]

Issue is still there in 2018. Happy 3 year anniversary (almost)!

[ganeshgowtham]

Issue is fixed, this might be because of synchronization.

On Jan 26, 2018 11:25 PM, "Alexandre M. Reis" notifications@github.com wrote:

Issue is still there in 2018. Happy 3 year anniversary (almost)!

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/OfficeDev/ews-java-api/issues/276#issuecomment-360856710, or mute the thread https://github.com/notifications/unsubscribe-auth/ADTVbwU6_jJSI6pzX9GSE4AwJVB6CLekks5tOhGPgaJpZM4D4k18 .