582776 - Thread-safe string/namespace interning

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Virtual Machine, defect)

Description

[Simon Wilkinson]

A performant implementation of thread-safe string interning will be necessary for a multi-threaded VM.

This is a tracking bug for any schemes we come up with.

The initial patch is very simple: interning operations are just protected by a lock. However, as the interning operation can trigger a ZCT reap, unfortunately this lock has to be one of the safepointing-aware variety from bug 575544.

Comment 1

[Simon Wilkinson]

Attachment: Initial patch

This patch is polluted by other bits of thread-safety work in AvmCore. The only relevant bits are those dealing with STRING_INTERN_LOCKER

Comment 2

[Simon Wilkinson]

Attachment: Latest. TR rev 6090. Patch queue rev 276

Comment 3

[Simon Wilkinson]

(In reply to comment #2)
> Created attachment 525935 [details] [diff] [review]
> Latest. TR rev 6090. Patch queue rev 276

Note the use of GCAutoCollectionDisable to prevent deadlocks when trying to allocate a String when holding the interning lock.

Also note that rehashing is disabled when the intern table is inspected from AvmCore::isInternedUint. This is an optimization so that the interning lock does not need to be acquired.

Comment 4

[Sylvestre Ledru [:Sylvestre]]

Tamarin is a dead project now. Mass WONTFIX.

Comment 5

[Sylvestre Ledru [:Sylvestre]]

Tamarin isn't maintained anymore. WONTFIX remaining bugs.