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 Topic: rotatelogs.exe -p option causing CPU spike |
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rguilbault
Joined: 25 Jul 2015
Posts: 7
Location: USA
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 Posted: Wed 12 Aug '15 18:23 Post subject: rotatelogs.exe -p option causing CPU spike |
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I recently spent some time trying to cleanup how we're recommending configuration of apache in terms of logfiles (for the purposes of writing parsers/analyzers, etc). one of the items undertaken was causing maintenance of the logfiles (as they'll be more verbose), which I opted to use the -p option to launch a process to archive the older files.
here's my config:
| Code: |
ErrorLog "|bin/rotatelogs.exe -p maint/MaintainLogs.bat -l logs/error.%Y%m%d.log 86400"
CustomLog "|bin/rotatelogs.exe -p maint/MaintainLogs.bat -l logs/access.%Y%m%d.log 86400" access
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on my Windows 8.1 laptop, rotatelogs is happy and my .bat file is invoked as hoped for, etc. there are 2 httpd process, each of which has an instance of rotatelogs for error and one for access.
on one of the developer's Windows 7 laptop and our central development Windows 2008 R2 DataCenter server, however, the main httpd process kicks off 2 rotatelogs and the child httpd process kicks off only 1 (for error, if that is interesting).
unfortunately, the rotatelogs for error for the watchdog process is spiking the CPU -- the callstack reported from processexplorer is usually:
| Code: | ntoskrnl.exe!memset+0x82f
ntoskrnl.exe!IoFreeErrorLogEntry+0x3b3
ntoskrnl.exe!KeSynchronizeExecution+0x692
ntoskrnl.exe!KeStackAttachProcess+0x1ba6
ntoskrnl.exe!KeStackAttachProcess+0x1207
ntoskrnl.exe!PsReturnProcessNonPagedPoolQuota+0x84d
ntoskrnl.exe!ObCheckObjectAccess+0x971
ntoskrnl.exe!ObCheckObjectAccess+0xd7f
ntoskrnl.exe!KeSynchronizeExecution+0x3a23
ntdll.dll!NtUnmapViewOfSection+0xa
wow64.dll!Wow64EmulateAtlThunk+0x84cb
wow64.dll!Wow64SystemServiceEx+0xd7
wow64cpu.dll!TurboDispatchJumpAddressEnd+0x2d
wow64.dll!Wow64SystemServiceEx+0x1ce
wow64.dll!Wow64LdrpInitialize+0x42a
ntdll.dll!RtlUniform+0x6e6
ntdll.dll!EtwEventSetInformation+0x15158
ntdll.dll!LdrInitializeThunk+0xe
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the contents of my batch file is fairly tame:
| Code: |
@echo off
set LOGFILE=%1
set THISDIR=%~dp0%
"%THISDIR%magic_console.exe" MaintainLogs.mas %LOGFILE%
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which is just launching a program that does the maintenance. I inserted a call to EVENTCREATE just before the program call in order to log the commandline (in case there was a problem with my program call) but nothing logs, so I am pretty certain the batch file is not getting hit in the problematic instances. there are no entries logged to event viewer from rotatelogs and removing the -p switch makes everything hunky dory again.
the version of rotatelogs.exe shows 2.4.12.0, which I downloaded from here:
Apache, 2.4.12, win32:
sourced: https://www.apachelounge.com/download/ - 03/24/2015
does anyone have any guidance on what might be happening/where to go next? |
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rguilbault
Joined: 25 Jul 2015
Posts: 7
Location: USA
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| Posted: Wed 12 Aug '15 22:10 Post subject: |
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I was able to compile rotatelogs.exe with some trap code added, e.g.:
| Code: | int main (int argc, const char * const argv[])
{
char buf[BUFSIZE];
apr_size_t nRead, nWrite;
apr_file_t *f_stdin;
apr_file_t *f_stdout;
apr_getopt_t *opt;
apr_status_t rv;
char c;
const char *opt_arg;
const char *err = NULL;
#if APR_FILES_AS_SOCKETS
apr_pollfd_t pollfd = { 0 };
apr_status_t pollret = APR_SUCCESS;
int polltimeout;
#endif
FILE *f = fopen("C:\\Program Files (x86)\\Apache\\bin\\!stderr.log","w");
unsigned int pid = GetProcessId(GetCurrentProcess());
fprintf(f, "[%u] 0\n", pid);
fflush(f);
apr_app_initialize(&argc, &argv, NULL);
fprintf(f, "[%u] 1\n", pid);
fflush(f);
atexit(apr_terminate);
fprintf(f, "[%u] 2\n", pid);
fflush(f);
memset(&config, 0, sizeof config);
memset(&status, 0, sizeof status);
status.rotateReason = ROTATE_NONE;
apr_pool_create(&status.pool, NULL);
fprintf(f, "[%u] 3\n", pid);
fflush(f);
apr_getopt_init(&opt, status.pool, argc, argv);
fprintf(f, "[%u] 4\n", pid);
fflush(f);
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I find that the rotatelogs.exe spawned from the child httpd process logs:
[9048] 0
[9048] 1
[9048] 2
[9048] 3
[9048] 4
[9048] 5: v - (null)
[9048] 5: p - maint/MaintainLogs.bat
[9048] prog: maint/MaintainLogs.bat
[9048] prog (after signal)
[9048] 5: l - (null)
[9048] 6
[9048] 7
[9048] 8
but the rotatelogs associated to the watchdog process are *not* putting anything to the log (in this test, it would be either pid 6768 or 5516).
as I begin logging before any function or loop is called, I'm thoroughly confused. and the references in the callstack all seem to point to https://msdn.microsoft.com/en-us/library/windows/desktop/hh447256%28v=vs.85%29.aspx or https://msdn.microsoft.com/en-us/library/windows/desktop/ms682489%28v=vs.85%29.aspx. |
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rguilbault
Joined: 25 Jul 2015
Posts: 7
Location: USA
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| Posted: Wed 12 Aug '15 22:16 Post subject: |
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lucky capture of a new/interesting callstack, perhaps:
ntoskrnl.exe!KeWaitForMultipleObjects+0xc0a
ntdll.dll!ZwMapViewOfSection+0xa
wow64.dll!Wow64EmulateAtlThunk+0x8325
wow64.dll!Wow64SystemServiceEx+0x1a8
wow64cpu.dll!TurboDispatchJumpAddressEnd+0x2d
wow64.dll!Wow64SystemServiceEx+0x1ce
wow64.dll!Wow64LdrpInitialize+0x42a
ntdll.dll!RtlUniform+0x6e6
ntdll.dll!RtlCreateTagHeap+0xa7
ntdll.dll!LdrInitializeThunk+0xe
ntdll.dll!ZwQuerySystemInformation+0x12
kernel32.dll!CreateToolhelp32Snapshot+0x5b
rotatelogs.exe!apr_proc_wait_all_procs+0xa5
rotatelogs.exe!post_rotate+0xc7
rotatelogs.exe!doRotate+0x211
rotatelogs.exe!main+0x483
rotatelogs.exe!__tmainCRTStartup+0x122
kernel32.dll!BaseThreadInitThunk+0x12
ntdll.dll!RtlInitializeExceptionChain+0x63
ntdll.dll!RtlInitializeExceptionChain+0x36 |
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rguilbault
Joined: 25 Jul 2015
Posts: 7
Location: USA
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| Posted: Thu 13 Aug '15 0:31 Post subject: |
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narrowing down futher, apr_proc_wait_all_procs returns APR_CHILD_DONE if there are no existing processes:
| Code: | if (nActive == 0) {
rv = APR_CHILD_DONE;
proc->pid = -1;
}
return rv;
} |
so the post-rotate logic gets caught up:
| Code: | while (apr_proc_wait_all_procs(&proc, NULL, NULL, APR_NOWAIT, pool) == APR_CHILD_DONE)
/* noop */; |
it almost feels like this should be != APR_CHILD_DONE (though it confuses me why I don't see the CPU spike on my laptop). |
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James Blond
Moderator
Joined: 19 Jan 2006
Posts: 7371
Location: Germany, Next to Hamburg
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rguilbault
Joined: 25 Jul 2015
Posts: 7
Location: USA
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