On Sat, 16 Jan 2021 12:40:47 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
> As noted by the reporter in the comments of > https://bugs.openjdk.java.net/browse/JDK-7146776, the `URLStreamHandler` in > its `getHostAddress` is incorrectly synchronizing on the `URLStreamHandler` > instance, instead of synchronizing on the `URL` instance that is being passed > to that method. > > The implementation of `URLStreamHandler#getHostAddress` checks for the > (package private) `hostAddress` member of the passed `URL` and if it isn't > set then does a DNS lookup to get the address and finally sets the > `hostAddress` member of the `URL` to this returned address. The access to > `hostAddress` of `URL` needs to be `synchronized` since it can be updated (in > a different thread) in the `URL#set` methods. > > The commit here removes the synchronization from the > `URLStreamHandler#getHostAddress` and moves the entire implementation into a > new (package private) `URL#getHostAddress` method and then calls this new > method from the `URLStreamHandler#getHostAddress`. I decided to do it this > way instead of just leaving the implementation in > `URLStreamHandler#getHostAddress` and synchronizing on the passed `URL` > instance, since IMO, this makes it much more easier to see (in one place > within the `URL` class) what the synchronization requirements are when > dealing with the `hostAddress`. Furthermore, this now allows the > `hostAddress` to be made a `private` member (which I have done in this > commit) instead of the previous package private access. I checked that no > other code tries to access this package private `URL#hostAddress`. > > I can't think of an easy way to add a jtreg test for this change, so I > haven't added one. This pull request has now been integrated. Changeset: db9c114d Author: Jaikiran Pai <j...@openjdk.org> URL: https://git.openjdk.java.net/jdk/commit/db9c114d Stats: 45 lines in 2 files changed: 25 ins; 15 del; 5 mod 7146776: deadlock between URLStreamHandler.getHostAddress and file.Handler.openconnection Reviewed-by: alanb, chegar ------------- PR: https://git.openjdk.java.net/jdk/pull/2109
