SRU Template prepared and uploaded for the SRU Teams consideration.
** Description changed:
+ [Impact]
+
+ * apache2 reload can fill up the scorecard with graceful reastarting
+ workers to an amount that it is unable to serve more requests.
+
+ * Backport fix from upstream to avoid the issue
+
+ [Test Case]
+
+ * In commend #8 I outlined some steps to fill up the scorecard with
+ Gracefully stopping processes. But that never triggered the reported
+ bug of eventually breaking new requests for me (It is still good to
+ verify some busy tests on this part of the apache code)
+ -> Therefore one of the reporters of the bug tested the ppa quite a
+ while on his main machines that formerly were affected by the issue.
+ -> no clear "do this then X happens" test case steps
+
+ [Regression Potential]
+
+ * It is a rather complex code change in the mpm event handling.
+ Only the first change is to code, the other two are for the
+ documentation to match.
+ We tested some apache benchmarks to check the effect, but found neither
+ a positive nor negative impact in general (other than the bug being
+ resolved). Yet if people rely on very specific behavior of the mpm
+ handling that might change a bit.
+ It will change for the good of it, but always remember xkcd.com/1172
+
+ TL;DR: IMHO it clearly has a ">none" regression potential on the mpm
+ event handling
+
+
+ [Other Info]
+
+ * Since this is hard to test we had a 2+ week test on the ppa, see
+ comments c#8 - c#15
+
+ * It clearly is a fix for some (e.g. the reporter of the bug), but I'd
+ understand if the SRU Team would rate it as feature and deny it for an
+ SRU - depends on the POV, certainly worth to be reviewed at least.
+
+
+ ----
+
+
On the clean install Ubuntu 14.04 with Apache without almost any client
load the Apache server with the command "service apache2 reload" itself
allocates slots marked with "Gracefully finishing" for which rejects new
connections.
For full rejection of new requests is sufficient to perform 4x command
"service apache2 reload".
Ubuntu 14.04.2 LTS
Apache 2.4.7-ubuntu4.4 (mpm_event)
Kernel 2.16.0-30-generic
-
Reproduce problem:
#################################################
1/ service apache2 start
______________________________________________________W_________
___________.....................................................
......................
2/ service apache2 reload
.........................GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
GGGGGGGGGGG__________________________________________________W__
______________________
3/ service apache2 reload
___W_____________________GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
GGGGGGGGGGG__________________________________________________...
......................
4/ service apache2 reload
GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG___
W_____________________
- 5/ service apache2 reload -> Server Apache not responding
+ 5/ service apache2 reload -> Server Apache not responding
With logs in apache error log file:
... [mpm_event:error] [pid 9381:tid 1234563234] AH00485: scoreboard is full,
not at MaxRequestWorkers
...
#################################################
-
- My workaround was change to MPM module from "mpm_event" to "mpm_worker".
+ My workaround was change to MPM module from "mpm_event" to
+ "mpm_worker".
** Changed in: apache2 (Ubuntu Xenial)
Status: Incomplete => In Progress
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https://bugs.launchpad.net/bugs/1466926
Title:
reload apache2 with mpm_event cause scoreboard is full
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