263767 - premature out of memory allocating lots of small objects

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Bob Clary [:bc] (inactive)]

If you attempt to quickly create large number of small objects using either |new
ClassName()| or by returning instances {propname: ''} for example, you will get
out of memory errors even though you still have plenty of memory.

On the attached test case on my dual xeon with 1G of ram, I see 

max objects
315,000      - no error, refresh page gc's the memory
316,000      - no error, refresh page pegs cpu and does not gc memory
317,000      - out of memory, browser becomes unstable

I reproduced this in winxpsp2 using Mozilla 1.8a5 on a xeon with 1G and a
pentium M with 512M. In Mozilla 1.7.x the browser hangs at about the same place
but does not show the out of memory error.

Approximate memory usage of about 100Meg

Comment 1

[Bob Clary [:bc] (inactive)]

Attachment: testcase 500,000 objects

Comment 2

[Bob Clary [:bc] (inactive)]

Running the testcase, I still get the out of memory error in 1.7.6, but not in
trunk builds. However the script appears to never complete in the trunk, cpu
usage drops unless you attempt to use the UI, memory usage stops increasing and
the app becomes unresponsive.

Comment 3

[Ed Voas]

FWIW, we are seeing this same bug in Konfabulator. We're using an older engine at this point (1.5 or 1.6, I 
can't remember), but it looks like it's still happening from the above comments.

Comment 4

[Brendan Eich [:brendan]]

Ed, can you try a recent engine to be sure?  We should be API compatible.  It
would help to confirm the identity of the bug you are seeing with the old engine.

/be

Comment 5

[Bob Clary [:bc] (inactive)]

I tried this in today's nightly ff 1.4.1 and it ran for a very long long time
before crashing when I tried to focus chatzilla. In today's debug trunk build it
ended very quickly with out of memory. I'll try to get a stack for the 1.4.1 build.

Comment 6

[Bob Clary [:bc] (inactive)]

I am now getting out of memory in 1.4.1 nightly and cvs builds so I can't
reproduce my earlier comment. I did crash once in 1.4.1 nightly after attempting
to open the js console after the out of memory error occured.

Comment 7

[Bob Clary [:bc] (inactive)]

wfm 1.8, 1.9 winxp/linux