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Posted to dev@hc.apache.org by "Oleg Kalnichevski (Jira)" <ji...@apache.org> on 2021/09/01 20:43:00 UTC
[jira] [Resolved] (HTTPCORE-683) H2ConnPool bug (stuck poolEntry)
[ https://issues.apache.org/jira/browse/HTTPCORE-683?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Oleg Kalnichevski resolved HTTPCORE-683.
----------------------------------------
Resolution: Fixed
> H2ConnPool bug (stuck poolEntry)
> --------------------------------
>
> Key: HTTPCORE-683
> URL: https://issues.apache.org/jira/browse/HTTPCORE-683
> Project: HttpComponents HttpCore
> Issue Type: Bug
> Components: HttpCore
> Affects Versions: 5.1.1
> Environment: Linux / Ubuntu / openjdk version "1.8.0_292"
> Reporter: Sylvain POGNANT
> Priority: Major
> Fix For: 5.1.2, 5.2-alpha1
>
>
> There is an implementation problem in *AbstractIOSessionPool.getSessionInternal()*
> Wrong pattern (starting line 190 in httpcore5-5.1.1) :
> if (poolEntry.sessionFuture == null) {
> *poolEntry.sessionFuture =* connectSession(
> namedEndpoint,
> connectTimeout,
> new FutureCallback<IOSession>() {
>
> ...
>
> @Override
> public void failed(final Exception ex) {
> synchronized (poolEntry) {
> poolEntry.session = null;
> *poolEntry.sessionFuture = null;*
> ...
> }
> }
> ...
> });
> In case of a synchronous failure during connectSession (for example : UnknownHostException), the sessionFuture cleanup in the failed() callback (line 216) is executed +before+ poolEntry.sessionFuture is assigned with the return value of connectSession (line 191)
> Thus, after the failure, a cancelled future is assigned to poolEntry.sessionFuture and never cleaned up !
> This result in a stalled entry in the pool because the _if (poolEntry.sessionFuture == null)_ condition will no longer return true.
>
> *Quick Reproducer*
> H2AsyncClientBuilder httpClientBuilder = HttpAsyncClients.customHttp2()
> .setDefaultRequestConfig(RequestConfig.custom()
> .setConnectTimeout(5000, TimeUnit.MILLISECONDS)
> .setResponseTimeout(5000, TimeUnit.MILLISECONDS)
> .build())
> .setH2Config(H2Config.custom()
> .setPushEnabled(false)
> .build());
>
> CloseableHttpAsyncClient client = httpClientBuilder.build();
> client.start();
>
> for(int n=1;n<=2;n++)
> {
> System.out.println("Try #"+n);
>
> HttpHost targetHost = new HttpHost(URIScheme.HTTPS.getId(), "invalidhost-gfhsgfxyzd.com", 443);
> SimpleHttpRequest request = new SimpleHttpRequest("GET", targetHost, "/");
>
> Future<SimpleHttpResponse> responseFuture = client.execute(request, null);
> try
> {
> responseFuture.get(); // {color:#FF0000}*HANGS FOREVER at Try #2*{color}
> }
> catch (ExecutionException e)
> {
> e.printStackTrace();
> }
> }
>
> *Quick Fix*
> Cleaning the sessionFuture immediately after connectSession() returns in case its already done fixes the issue :
> (Line 234)
> + if (poolEntry.sessionFuture != null && poolEntry.sessionFuture.isDone())
> + poolEntry.sessionFuture = null;
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