Bug 195892

Summary: REGRESSION: (r243032) inspector/model/remote-object.html is failing.
Product: WebKit Reporter: Truitt Savell <tsavell>
Component: Tools / TestsAssignee: Mark Lam <mark.lam>
Severity: Normal CC: fpizlo, jlewis3, keith_miller, lforschler, msaboff, rmorisset, ryanhaddad, saam, tzagallo, webkit-bug-importer, ysuzuki
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=196008

Description Truitt Savell 2019-03-18 09:27:51 PDT
The following layout test is failing on Mac


Probable cause:

This test began failing near constantly after changes in https://trac.webkit.org/changeset/243032/webkit. 

Flakiness Dashboard:



I was able to reproduce this locally with command:
run-webkit-tests inspector/model/remote-object.html --iterations 100 -f

it fails often on 242032 but passes on 242031.
Comment 1 Truitt Savell 2019-03-18 09:30:58 PDT
marked failing in https://trac.webkit.org/changeset/243071/webkit until mark can fix this.
Comment 2 Radar WebKit Bug Importer 2019-03-18 09:40:54 PDT
Comment 3 Mark Lam 2019-03-21 10:10:43 PDT
Also from https://bugs.webkit.org/show_bug.cgi?id=195827#c8:

It appears that changes in https://trac.webkit.org/changeset/243032

Are causing a JSC failure on the Debug queue



Regression range is 243030 to 243033
Comment 4 Mark Lam 2019-03-23 21:11:37 PDT
From the rollout ChangeLog:

The fix is incorrect: it relies on being able to determine liveness of an object in an ObjectPropertyCondition based on the state of the object's MarkedBit.  However, there's no guarantee that GC has run and that the MarkedBit is already set even if the object is live.  As a result, we may not re-install adaptive watchpoints based on presumed dead objects which are actually live.

I'm rolling this out, and will implement a more comprehensive fix to handle watchpoint liveness later.
Comment 5 Mark Lam 2019-03-23 21:12:08 PDT
*** Bug 196008 has been marked as a duplicate of this bug. ***
Comment 6 Mark Lam 2019-03-23 21:16:47 PDT
The rollout was landed in r243420: <http://trac.webkit.org/r243420>.