Add missing synchronization guards when accessing startedServers Set

[sebthom]

No description provided.

[mickaelistria]

Which problem is it fixing? Do you have steps to reproduce issues that are fixed with this patch?

[sebthom]

I saw that the synchronization blocks are missing while investigating the deadlocks.

The current code as is technically broken. Either all access paths need to be synchronized or none.

[mickaelistria]

Either all access paths need to be synchronized or none.

Actually, if the structure is sufficiently thread-safe on access, read-only operations may not need to be synchronized.

[sebthom]

The methods that are currently unguarded iterate over a set that might by modified by other methods at the same time. This basically begs for potential ConcurrentModificationExceptions.

I would agree with you that this change might not be required - but only if LanguageServiceAccessor was an internal class where you have control over which of its methods are called when by other code. But this is a public class where all methods can be concurrently invoked by external code as pleased.

[mickaelistria]

OK, thanks!