For B2G's gaia repository we are currently using xpcshell[1] as our
command line JS runner. I was noticing some horrible inconsistencies in
terms of blowing the JS stack when we were trying to use the esprima JS
parser[2] that varied by the platform and build type.
The nutshell is that the #defines at
http://dxr.mozilla.org/mozilla-central/source/js/xpconnect/src/XPCJSRuntime.cpp#l2687
net us the following JS stack limits. (These are the limits when the JS
engine starts throwing "InternalError: too much recursion" and are
somewhat separate from actual native stack limits.)
linux (32 bit, non-debug): 512 KiB
windows (all builds): 900 KiB [3]
linux (32 bit, debug): 1 MiB
linux (64 bit, non-debug): 1 MiB
linux (64-bit, debug): 2 MiB
OS X (all): 7 MiB
For gaia's purposes, this inconsistency is not great. How should we
resolve this?
a) Make xpcshell try and pick more consistent values itself
b) Make xpcshell take a command line argument and call
JS_SetNativeStackQuota plus doing whatever it needs to back that up with
an appropriate platform stack (possibly by re-exec()ing). (Similar to
node.js supporting --stack_size which defaults to 984 for me right now.)
c) Change xpconnect's hard-coded defaults
d) Change xpconnect to use jsnativestack.cpp's ability to tell us what
the platform stack size actually is and/or nsThread's knowledge of the
stack size it was created with. So on linux we'd use whatever 'ulimit
-s' is telling us to do, etc.
e) Don't use xpcshell for that! Are you crazy?!
f) Other
Thanks,
Andrew
1: Although in the future this might end up just being any xulrunner
"-app" capable build.
2: Since the esprima JS parser produces a parse-tree that's supposed to
confirm to what SpiderMonkey's Reflect API produces, we do have a
work-around, but I expect this stack issue to come up again in the future.
3: The windows limit could be higher by its current rationale;
https://bugzilla.mozilla.org/show_bug.cgi?id=582910 increased the
windows stack to 2 MiB from 1MiB.
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