Bug 139738

Summary:	[iOS] run-webkit-tests significantly slows down when running the last bunch of tests
Product:	WebKit	Reporter:	Daniel Bates <dbates>
Component:	Tools / Tests	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED CONFIGURATION CHANGED
Severity:	Normal	CC:	ap, bfulgham, ddkilzer, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	528+ (Nightly build)
Hardware:	iPhone / iPad
OS:	iOS 8.1

Description Daniel Bates 2014-12-17 11:49:59 PST

I noticed when using run-webkit-tests to run iOS layout tests using WebKit1 an WebKit2 that the rate at which tests are run significantly slows down as run-webkit-tests nears completion. This behavior tends to be more noticeable when running large batches of tests (> 10000). I am using a Mac Pro with 2 x 2.66 GHz 6-Core Intel Xeon processors, 12 GB RAM, OS X Yosemite (14A378) with a debug build of WebKit at r177430.

I invoke run-webkit-tests to run tests using WebKit2 with a command line of the form:

Tools/Scripts/run-webkit-tests --ios-sim --runtime com.apple.CoreSimulator.SimRuntime.iOS-[...] --device-type com.apple.CoreSimulator.SimDeviceType.iPhone-5s --no-sample-on-timeout --results-directory layout-test-results-rebase -2 [...]

(I omit the argument -2 in the above command to run the specified tests using WebKit1).

When invoked with [...] as the empty string (i.e. to run the full suite of layout tests), run-webkit-test will run 24 instances of WebKitTestRunnerApp.app in parallel.

Comment 1 Radar WebKit Bug Importer 2014-12-17 12:04:19 PST

<rdar://problem/19282201>

Comment 2 Alexey Proskuryakov 2014-12-17 13:04:43 PST

Is it just that some workers finish, and there are only a few of them remaining at the end? Running run-webkit-tests with --debug-rwt-logging should tell.