Does PHP programming need to use locks?

Does PHP programming need to use locks?

Yes.

Because in order to ensure the effectiveness and integrity of the operation, the concurrent state needs to be converted into the serial state through the lock mechanism to solve the resource competition problem caused by high concurrency. As one of the locking mechanisms, PHP's file lock is also designed to cope with resource competition.

Assume an application scenario. In the case of large concurrency, fwrite is used to write data to the end of the file multiple times in an orderly manner. What will happen without locking? Multiple ordered write operations are equivalent to one transaction, and we need to ensure the integrity of this transaction at this time.

If we have two programs writing data to a file at the same time, in order to ensure the integrity of the data, we can add a file lock and let program 1 execute first. After program 1 is executed, unlock it and then Let program 2 execute. The implementation code is as follows:

$fp = fopen('test.txt',"a");
$count = 10;
if (flock($fp, LOCK_EX)) {
for($i=1;$i<$count;$i++){
fwrite($fp, &#39;text2_&#39;.$i."rn");
echo "test2".date(&#39;h:i:s&#39;) . "
";
sleep(1); 
echo "test2".date(&#39;h:i:s&#39;);
}
flock($fp , LOCK_UN);
}else{
echo "Couldn&#39;t lock the file !";
}
fclose($fp);

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