Closed
Bug 488414
Opened 16 years ago
Closed 16 years ago
TM: investigate if it is sound to call js_GenerateShape from the trace
Categories
(Core :: JavaScript Engine, defect, P1)
Core
JavaScript Engine
Tracking
()
RESOLVED
FIXED
People
(Reporter: igor, Assigned: igor)
References
Details
(Keywords: fixed1.9.1, Whiteboard: fixed-in-tracemonkey)
Attachments
(1 file, 5 obsolete files)
(deleted),
patch
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igor
:
review+
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Details | Diff | Splinter Review |
Currently record_SetPropHit adds to the trace code to call js_AddProperty. That in turn may call js_AddScopeProperty which in turns calls js_GenerateShape. When shape overflows, the latter calls js_GC(). Is it expected?
Comment 1•16 years ago
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Looks like a js_LeaveTrace is needed, at the least. /be
Flags: blocking1.9.1?
Assignee | ||
Comment 2•16 years ago
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I suspect a good solution to this and other cache bugs would be to change js_GenerateShape not to call js_GC. Rather on shape overflow it should just disable the cache and schedule the GC to happen at a later point.
Comment 3•16 years ago
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Along the same lines, we shouldn't renumber shapes at every GC. We should use a separate heuristics for that.
Assignee | ||
Comment 4•16 years ago
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I am going to implement that idea of just scheduling, not running, the GC from js_GenerateShape. It still would mean that the trace that calls js_AddProperty must guard that shape has not overflow, but that is simple.
Assignee: general → igor
Updated•16 years ago
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Priority: -- → P2
Updated•16 years ago
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Flags: blocking1.9.1? → blocking1.9.1+
Comment 5•16 years ago
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If we want this for 3.5 it has to be P1 and blocking b4 IMO. This is going to allow GC-ing during trace execution. Lots of potential fallout. Brendan thinks it might be possible to hack this short-term though.
Assignee | ||
Comment 7•16 years ago
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To Robert Sayre: I have a patch that I can finish today, but it depends on 487039. If that sounds OK, I would suggest to make that bug P1 as well.
Comment 8•16 years ago
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Igor: if that's the case, please re-nominated bug 487039 with a reason in that bug.
Assignee | ||
Comment 9•16 years ago
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The patch implements that idea of just scheduling, not calling the GC on the shape overflow. The most unclear part is js_AddProperty built-in changes. Currently the function returns false both to indicate OOM error and simple property mismatch. The jited code guards towards the OOM_EXIT on false. Assuming that this is the right thing to do, the patch also make function to return false on shape overflow.
Assignee | ||
Comment 10•16 years ago
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(In reply to comment #9) > Created an attachment (id=373478) [details] > v1 - work in progress This patch is build on top of the patch from bug 487039 comment 19.
Assignee | ||
Updated•16 years ago
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Attachment #373478 -
Attachment is patch: true
Attachment #373478 -
Attachment mime type: application/octet-stream → text/plain
Assignee | ||
Comment 11•16 years ago
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The new version fixes the nested GC lock that v1 has and makes sure that single-threaded build compiles and avoids useless gcLocked flag in function signatures.
Attachment #373478 -
Attachment is obsolete: true
Assignee | ||
Comment 12•16 years ago
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Asking for comments on js_AddProperty built-in changes - is just returning false on shape overflow is the right thing there?
Attachment #373479 -
Attachment is obsolete: true
Attachment #373567 -
Flags: review?(gal)
Updated•16 years ago
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Attachment #373567 -
Flags: review?(gal)
Attachment #373567 -
Flags: review?(brendan)
Attachment #373567 -
Flags: review+
Comment 13•16 years ago
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Comment on attachment 373567 [details] [diff] [review] v3 I like it. The "Updated by js_GenerateShape" is unclear to me. Could you extend that comment? Brendan should look at this too. Shouldn't we use ATOMIC_INC from PR for concurrent updates to shapeGen?
Assignee | ||
Comment 14•16 years ago
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The new patch updates comments to make it clear that, compared with js_GenerateShape, js_RegenerateShapeForGC does not need to do atomic increments. It also fixed a bug where gcIsNeeded would be cleared by SET_SLOT pseudo-GC runs.
Attachment #373567 -
Attachment is obsolete: true
Attachment #373577 -
Flags: review?(brendan)
Attachment #373567 -
Flags: review?(brendan)
Comment 15•16 years ago
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Comment on attachment 373577 [details] [diff] [review] v4 >+#ifdef JS_THREADSAFE >+# define js_TriggerAllOperationCallbacks(rt, gcLocked) \ >+ js_TriggerAllOperationCallbacks (rt, gcLocked) >+#else >+# define js_TriggerAllOperationCallbacks(rt, gcLocked) \ >+ js_TriggerAllOperationCallbacks (rt) >+#endif The space hack is a little too cute, but why use it at all #ifdef JS_THREADSAFE? Rather, define the macro only for !JS_THREADSAFE. >+js_IsDisabledPropertyCache(JSContext *cx) Rename to js_IsPropertyCacheDisabled. >+#ifdef JS_THREADSAFE >+# define js_GenerateShape(cx, gcLocked) js_GenerateShape (cx, gcLocked) >+#else >+# define js_GenerateShape(cx, gcLocked) js_GenerateShape (cx) >+#endif Same comment as above. >@@ -3445,29 +3462,31 @@ js_GC(JSContext *cx, JSGCInvocationKind > > /* > * We assume here that killing links to parent and prototype objects > * does not create garbage (such objects typically are long-lived and > * widely shared, e.g. global objects, Function.prototype, etc.). We > * collect garbage only if a racing thread attempted GC and is waiting > * for us to finish (gcLevel > 1) or if someone already poked us. > */ >- if (rt->gcLevel == 1 && !rt->gcPoke) >+ if (rt->gcLevel == 1 && !rt->gcPoke &&! rt->gcIsNeeded) &&! => && ! > goto done_running; > > rt->gcLevel = 0; > rt->gcPoke = JS_FALSE; > rt->gcRunning = JS_FALSE; > #ifdef JS_THREADSAFE > rt->gcThread = NULL; > #endif > gckind = GC_LOCK_HELD; > goto restart_at_beginning; > } > >+ /* Clear gcIsNeeded now, when we are about to start a normal GC cycle. */ >+ rt->gcIsNeeded = JS_FALSE; > JS_UNLOCK_GC(rt); > > #ifdef JS_TRACER > if (JS_ON_TRACE(cx)) > goto out; > #endif Is the gcIsNeeded = false premature in light of the JS_TRACER code? >@@ -124,18 +121,17 @@ js_FillPropertyCache(JSContext *cx, JSOb > jsuword vword; > ptrdiff_t pcoff; > jsuword khash; > JSAtom *atom; > JSPropCacheEntry *entry; > > JS_ASSERT(!cx->runtime->gcRunning); > cache = &JS_PROPERTY_CACHE(cx); >- pc = cx->fp->regs->pc; >- if (cache->disabled || (cx->fp->flags & JSFRAME_EVAL)) { >+ if (js_IsDisabledPropertyCache(cx) || (cx->fp->flags & JSFRAME_EVAL)) { Separate bug: turning off the cache from eval is no longer necessary, given the scripsToGC-based garbage collection of eval-compiled scripts, your fix to avoid caching non-global natives at the end of the scope chain (subsuming with statement disabling), and other fixes. Or so it seems to me! Could you file if you concur? Thanks. >+ if (js_IsDisabledPropertyCache(cx)) { >+ /* >+ * js_GenerateShape could not recover from shape's s/shape's/rt->shapeGen's/ >+ sprop_changed: >+ oom_exit: > JS_UNLOCK_SCOPE(cx, scope); > return JS_FALSE; Looks good -- could use do-while(0) with break to avoid gotos, not sure it's any simpler. js_AddProperty is BOOL_RETRY (please correct me if I'm wrong) so failing causes the triggered trace to exit back to the interpreter, to retry the add. >+#ifdef JS_THREADSAFE >+# define js_TriggerGC(cx, gcLocked) js_TriggerGC (cx, gcLocked) >+#else >+# define js_TriggerGC(cx, gcLocked) js_TriggerGC (cx) >+#endif Ditto early comment on space hack confinement to !JS_THREADSAFE. Great to have the deferred trigger machinery -- I needed it during Firefox 3 propcache dev era, should have done it then for shape gen at least (sans operation callback changes for Fx3.5). /be
Attachment #373577 -
Flags: review?(brendan) → review+
Assignee | ||
Comment 16•16 years ago
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addressing all the issues from the comment 15 In js_AddProperty built-in I replaced all those different goto labels by single exit_trace. The build it is bool_retry indeed. An alternative version using do-while(0) (or rather for(;;) { ... return true; }) was uglier IMO due to excessive indentation.
Attachment #373577 -
Attachment is obsolete: true
Attachment #373590 -
Flags: review+
Assignee | ||
Comment 18•16 years ago
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The new patch adds missing JS_TREADSAFE ifdef around JS_ASSERT(cx->requestDepth > 0) in js_TriggerGC.
Attachment #373590 -
Attachment is obsolete: true
Attachment #373632 -
Flags: review+
Assignee | ||
Comment 19•16 years ago
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https://hg.mozilla.org/tracemonkey/rev/7523cef76351
Whiteboard: fixed-in-tracemonkey
Comment 20•16 years ago
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http://hg.mozilla.org/mozilla-central/rev/7523cef76351
Status: NEW → RESOLVED
Closed: 16 years ago
Resolution: --- → FIXED
Comment 21•16 years ago
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http://hg.mozilla.org/releases/mozilla-1.9.1/rev/3c718b1c7b03
Keywords: fixed1.9.1
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Comment 22•16 years ago
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This failed to build with liveconnect enabled. See http://hg.mozilla.org/releases/mozilla-1.9.1/rev/81e683c58238 and http://hg.mozilla.org/releases/mozilla-1.9.1/rev/9244eedd7d25
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Description
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