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[2010-10-17 08:45 UTC] vuliad at gmail dot com
Description:
------------
PHP Version 5.3.3 (cannot select it in phpversion here)
System FreeBSD 6.3-STABLE FreeBSD 6.3-STABLE
PHP API 20090626
PHP Extension 20090626
Zend Extension 220090626
Zend Extension Build API220090626,NTS
PHP Extension Build API20090626,NTS
Version 3.1.4
MMAP Support Enabled
MMAP File Mask /tmp/apc.EyYwAm
Locking type File Locks
Revision $Revision: 301663 $
Build Date Oct 12 2010 13:40:15
Directive Local Value
apc.cache_by_default On
apc.canonicalize On
apc.coredump_unmap Off
apc.enable_cli Off
apc.enabled On
apc.file_md5 Off
apc.file_update_protection 2
apc.filters no value
apc.gc_ttl 3600
apc.include_once_override Off
apc.lazy_classes Off
apc.lazy_functions Off
apc.max_file_size 512M
apc.mmap_file_mask /tmp/apc.EyYwAm
apc.num_files_hint 1000
apc.preload_path no value
apc.report_autofilter Off
apc.rfc1867 Off
apc.rfc1867_freq 0
apc.rfc1867_name APC_UPLOAD_PROGRESS
apc.rfc1867_prefix upload_
apc.rfc1867_ttl 3600
apc.shm_segments 1
apc.shm_size 512M
apc.slam_defense Off
apc.stat On
apc.stat_ctime Off
apc.ttl 0
apc.use_request_time On
apc.user_entries_hint 4096
apc.user_ttl 0
apc.write_lock On
_Sometimes_ apc_store saving "false" value.
apc_store("aaa","bbb") #returns true;
apc_fetch("aaa") #return false;
I write test(see Reproduce code) and results is:
storesTime: 0.00570511817932
testSteps: 100
StrRepeat multiple: 1
fetchTime: 0.00220680236816
stored: 100 values (100%)
exists: 5 values (5%)
fetched: 5 values (5%)
storesTime: 0.718439817429
testSteps: 10000
StrRepeat multiple: 1
fetchTime: 0.566982984543
stored: 10000 values (100%)
exists: 2528 values (25.28%)
fetched: 2528 values (25.28%)
after multiple refresh it always change beetween 2% and 90%
The problem is that TOO many variables cannot be cashed.
Looking in apc.php for User Cache Entries there are more of
Info testKey98
Ttl 0
Type user
Num Hits 0 (0.00%)
Mtime 2010/10/17 16:27:14
Creation Time 2010/10/17 16:27:14
Deletion Time None
Access Time 2010/10/17 16:27:14
Ref Count 0
Mem Size 580
Stored Value
false
The main problem here is that - Stored Value = false. Why
it's false and what it mean?
There are some more strange thing:
If i clear user cache, User Cached Entries in apc.php gives
"No data". BUT!! after store only one variable. and refresh
in User Cached Entries - it shows Many other Keys that were
stored before cache where flushed. it Stored Value gives
FALSE and it cannot be deleted with apc_delete from User
Cached Entries.
Reproduce code:
---------------
<?php
$prefix="testKey";
$testSteps=100;
$multiple=1;
$storeSuccessCount=0;
$fetchSuccessCount=0;
$existsSuccessCount=0;
$start=microtime(true);
for($i=0;$i<=$testSteps-1;$i++)
{
if(apc_store($prefix.$i,str_repeat("a",$multiple*$i)))
$storeSuccessCount++;
}
echo "storesTime: ".(microtime(true)-$start)."\n";
sleep(1);
$start=microtime(true);
for($i=0;$i<=$testSteps-1;$i++)
{
if(apc_fetch($prefix.$i))
$existsSuccessCount++;
if($val=apc_fetch($prefix.$i))
$fetchSuccessCount++;
}
echo "testSteps: ".$testSteps." \n";
echo "StrRepeat multiple: ".$multiple." \n";
echo "fetchTime: ".(microtime(true)-$start)."\n";
echo "stored: ".$storeSuccessCount." values (". (100*($storeSuccessCount/$testSteps))."%)\n";
echo "exists: ".$existsSuccessCount." values (". (100*($existsSuccessCount/$testSteps))."%)\n";
echo "fetched: ".$fetchSuccessCount." values (". (100*($fetchSuccessCount/$testSteps))."%)\n";
?>
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Last updated: Fri May 17 05:01:31 2024 UTC |
I also experience this bug on different boxes w/PHP 5.2.6 and PHP 5.3.3. APC version 3.1.4 (version 3.0.19 on these boxes works fine). It happens so often that I've wrapped apc_store in a function that does the store, and then an immediate fetch to compare against what was just stored. If it doesn't match, I repeat the store/fetch of the key until the values match. I log the number of times it takes until the store is successful. It seems to take between 1 and 7 tries, but eventually it will always work. Most common is success after 1 retry. It is not timing related... I've tired using a sleep(), etc., but the value will never show up no matter how long I give it (nor to different processes). The only way to get the store to work it just repeat it over and over. My function: function _APCStore($key, $value) { $retries = 0; while ( 1 ) { apc_store($key, $value, 0); $test = apc_fetch($key); if ( $test != $value ) { error_log('EBB:_APCStore: Failed '.($retries+1).' times'); $retries++; if ( $retries < 100 ) continue; else _FatalError("EBB:_APCStore: Unable to store value into APC!"); } break; } }