On Fri, 19 May 2023 15:46:14 GMT, Jesse Glick <d...@openjdk.org> wrote:

>> [JDK-6956385](https://bugs.openjdk.org/browse/JDK-6956385): 
>> `JarURLConnection` properly tracks any `InputStream` it itself opened, and 
>> correspondingly closes the `JarFile` if necessary (when caches are 
>> disabled). However if its underlying `FileURLConnection` was used to 
>> retrieve a header field, that would have caused a `FileInputStream` to be 
>> opened which never gets closed until it is garbage collected. This means 
>> that an application which calls certain methods on 
>> `jar:file:/…something.jar!/…` URLs will leak file handles, even if 
>> `URLConnection` caches are supposed to be turned off. This can delay release 
>> of system resources, and on Windows can prevent the JAR file from being 
>> deleted even after it is no longer in use (for example after 
>> `URLClassLoader.close`).
>> 
>> [JDK-8224095](https://bugs.openjdk.org/browse/JDK-8224095) was marked as a 
>> duplicate, but I think incorrectly. It refers to `FileURLConnection`, and 
>> seems to be complaining about the confusing API design of `URLConnection` 
>> generally: that it is an object which you might expect to be `Closeable` but 
>> in fact it is its `inputStream` which must be `close`d. In JDK-6956385, even 
>> when the caller _does_ specifically call `InputStream.close`, a file handle 
>> may be leaked.
>> 
>> I managed to build the JDK on both Linux and (Cygwin) Windows to confirm the 
>> fix via
>> 
>> 
>> ./build/…-x86_64-server-release/jdk/bin/java 
>> test/jdk/sun/net/www/protocol/jar/FileURLConnectionLeak.java
>> 
>> 
>> I also ran jtreg on Linux (this test and various others in nearby packages); 
>> on Windows the `make test` target just hung for some reason.
>> 
>> I marked the test `othervm` out of caution, since it is mutating global 
>> state, and if it fails will leak a handle and prevent scratch dir cleanup on 
>> Windows.
>> 
>> (This is my first contribution, at least after the move to GitHub, so let me 
>> know if something is missing here technically or stylistically. None of the 
>> contribution guides appear to be up to date.)
>
> Jesse Glick has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Leaving `FileURLConnection.is` non-null, and claiming `connected`, even 
> after `closeInputStream` 
> https://github.com/openjdk/jdk/pull/12871#discussion_r1199085883

Marked as reviewed by dfuchs (Reviewer).

I have run tier1, tier2, tier3, and several repeated runs of jdk_net in our CI 
and haven't observed any failures related to the proposed changes. As far as I 
am concerned, this looks good. I am going to approve, but it would good to have 
a second Reviewer in case I missed anything.

-------------

PR Review: https://git.openjdk.org/jdk/pull/12871#pullrequestreview-1436897162
PR Comment: https://git.openjdk.org/jdk/pull/12871#issuecomment-1557432162

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