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eclipse-ee4j / grizzly

Grizzly
https://eclipse-ee4j.github.io/grizzly
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Threads are not closed once Grizzly's HttpServer shuts down #2158

Closed arekfirus closed 1 year ago

arekfirus commented 2 years ago

I have found a strange behavior of Grizzly's HttpServer class. Once it is shutdown (using shutdown method not shutdownNow) not all resources are released.

The problem started to appear in 2.4.0 version and it is still present in 3.x. The problem was not present in 2.3.x. Please see attached project showing the behavior. grizzly_http_server_shutdown.tar.gz

I think the situation is caused by commenting the invocation of the shutdownNow method once all listeners are closed: https://github.com/javaee/grizzly/blob/master/modules/http-server/src/main/java/org/glassfish/grizzly/http/server/HttpServer.java#L388

To work around the problem, invocation of shutdownNow needs to be done manually (for example when the future, returned by the shutdown method, finishes).

The situation is the most problematic in tests when many instances of HttpServer can be created and destroyed in single JVM. In such cases it leads to memory leak.

pzygielo commented 2 years ago

@arekfirus - do you think your finding could be the cause for failing tests:

TCPNIOTransportTest.testMultiBind:139 » Bind Address already in use
...
TCPNIOTransportTest.testMultiBind:161 Server connection should be closed!
...
HttpResponseParseTest.testSimpleHeaders:71->doHttpResponseTest:181 » Bind Addr...

?

arekfirus commented 2 years ago

@pzygielo , my knowledge of Grizzly is quite limited but I think these problems are not correlated. The problems which you have mentioned are related to binding to network address. The shutdown method closes all network listeners correctly, so this two things should have nothing in common. At least at the first sight.

The shutdown method leaves the HttpServer in a strange state when it does accept no incoming connections (because the listeners are closed) but beside of that, everything still works and resources are not released. I am not sure if it was intentional.

I faced a problem of OOM appearing during tests after the upgrade of Grizzly and after the investigation I found that strange behavior.

pzygielo commented 2 years ago

Thanks for the details, @arekfirus.