[SR-2931] libdispatch `dispatch_suspend_timer` test needs robustification

[swift-ci]

Previous ID	SR-2931
Radar	None
Original Reporter	erg (JIRA User)
Type	Bug
Status	Resolved
Resolution	Won't Do

Additional Detail from JIRA

Votes	0
Component/s	libdispatch
Labels	Bug, Linux
Assignee	dgrove-oss (JIRA)
Priority	Medium

md5: b1a66dd63a8bf2dc1f3bfe6379f2bcb9

is duplicated by:

• SR-3110 libdispatch - FAIL dispatch_suspend_timer (exit status: 1)

Issue Description:

`dispatch_suspend_timer` test fails randomly in public CI tests.

Previous patch for a related failure:
https://bugs.swift.org/browse/SR-2856

https://ci.swift.org/view/swift-3.0-branch/job/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/247/console
https://ci.swift.org/view/swift-3.0-branch/job/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/249/console

```
PASS: dispatch_timer
PASS: dispatch_timer_short
PASS: dispatch_timer_timeout
PASS: dispatch_sema
FAIL: dispatch_suspend_timer
PASS: dispatch_timer_bit31
PASS: dispatch_timer_bit63
PASS: dispatch_timer_set_time
PASS: dispatch_starfish
PASS: dispatch_cascade
PASS: dispatch_data
PASS: dispatch_io_net
PASS: dispatch_select

Testsuite summary for libdispatch 1.3

1. TOTAL: 23

2. PASS: 22

3. SKIP: 0

4. XFAIL: 0

5. FAIL: 1

6. XPASS: 0

7. ERROR: 0

   See tests/test-suite.log
   Please report to https://bugs.swift.org

   Makefile:1352: recipe for target 'test-suite.log' failed
   make[3]: *** [test-suite.log] Error 1
   make[3]: Leaving directory '/home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/buildbot_incremental/libdispatch-linux-x86_64/tests'
   Makefile:1458: recipe for target 'check-TESTS' failed
   make[2]: *** [check-TESTS] Error 2
   make[2]: Leaving directory '/home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/buildbot_incremental/libdispatch-linux-x86_64/tests'
   Makefile:1741: recipe for target 'check-am' failed
   make[1]: *** [check-am] Error 2
   make[1]: Leaving directory '/home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/buildbot_incremental/libdispatch-linux-x86_64/tests'
   Makefile:456: recipe for target 'check-recursive' failed
   make: *** [check-recursive] Error 1
   /home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/swift/utils/build-script: fatal error: command terminated with a non-zero exit status 2, aborting
   /home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/swift/utils/build-script: fatal error: command terminated with a non-zero exit status 1, aborting
   Build step 'Execute shell' marked build as failure
   [xUnit] [INFO] - Starting to record.
   [xUnit] [INFO] - Processing JUnit
   [xUnit] [INFO] - [JUnit] - 1 test report file(s) were found with the pattern 'buildbot_incremental/swift-linux-x86_64/swift-test-results/x86_64-unknown-linux-gnu/lit-tests.xml' relative to '/home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10' for the testing framework 'JUnit'.
   [xUnit] [INFO] - Converting '/home/buildnode/jenkins/workspace/oss-swift-3.0-incremental-RA-linux-ubuntu-15_10/buildbot_incremental/swift-linux-x86_64/swift-test-results/x86_64-unknown-linux-gnu/lit-tests.xml' .
   [xUnit] [INFO] - Check 'Failed Tests' threshold.
   [xUnit] [INFO] - Check 'Skipped Tests' threshold.
   [xUnit] [INFO] - Setting the build status to FAILURE
   [xUnit] [INFO] - Stopping recording.
   [BFA] Scanning build for known causes...
   [BFA] No failure causes found
   [BFA] Done. 0s
   Email was triggered for: Failure - Any
   Sending email for trigger: Failure - Any
   An attempt to send an e-mail to empty list of recipients, ignored.
   Finished: FAILURE
   ```

[swift-ci]

Comment by Doug Coleman (JIRA)

`dispatch_suspend_timer` just failed again:

https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-15_10/8382/console

==================================================
[TEST] Dispatch Suspend Timer
[PID] 26603

[BEGIN] dispatch_source_timer_create
Actual: 0x162e180
Expected: 0x162e180
[PASS] dispatch_source_timer_create

[BEGIN] dispatch_source_timer_create
Actual: 0x16308a0
Expected: 0x16308a0
[PASS] dispatch_source_timer_create
tweedledee 1 (1)
tweedledee 2 (2)
tweedledee 3 (3)
suspending timer for 3 seconds
resuming timer

[BEGIN] tweedledee tick count
Actual: 3
Expected: 3
[PASS] tweedledee tick count

[BEGIN] tweedledee virtual tick count
Actual: 3
Expected: 3
[PASS] tweedledee virtual tick count
tweedledee 4 (7)
tweedledee 5 (8)
tweedledee 6 (9)

[BEGIN] tweedledee tick count
Actual: 6
Expected: 7
[FAIL] tweedledee tick count (dispatch_suspend_timer.c:96)
dispatch_suspend_timer.c:96

[BEGIN] tweedledee virtual tick count
Actual: 9
Expected: 9
[PASS] tweedledee virtual tick count

[BEGIN] finalizer ran
Actual: 0x16308a0
Expected: 0x16308a0
[PASS] finalizer ran

[BEGIN] Process exited
Actual: 0
Expected: 0
[PASS] Process exited
[PERF] wall time: 0.000152
[PERF] user time: 1.368000
[PERF] system time: 6.500000
[PERF] max resident set size: 19752
[PERF] page faults: 0
[PERF] swaps: 0
[PERF] voluntary context switches: 1879158
[PERF] involuntary context switches: 21
FAIL dispatch_suspend_timer (exit status: 1)

============================================================================
Testsuite summary for libdispatch 1.3

1. TOTAL: 22

2. PASS: 21

3. SKIP: 0

4. XFAIL: 0

5. FAIL: 1

6. XPASS: 0

7. ERROR: 0

[swift-ci]

Comment by Doug Coleman (JIRA)

https://ci.swift.org/job/oss-swift-3.0-package-linux-ubuntu-15_10/98/console

Failed again.

[swift-ci]

Comment by David Grove (JIRA)

Test disabled by #187

[swift-ci]

Comment by David Grove (JIRA)

Disabled test case for now; eventually need to revisit this test case along with the 10 other unreliable test cases and either make them reliable or set up a separate CI job for libdisapatch to run them.