[FIXED] When PHP exec function creates a process, where is it queued so that it can be removed programmatically or from command line?

Issue

I have a PHP script that runs the following code:

exec("ls $image_subdir | parallel -j8 tesseract $image_subdir/{} /Processed/OCR/{.} -l eng pdf",$output, $result_code);

The code runs, however, even after I terminate the PHP script and close the browser, it continues to create the pdf files (thousands). It has been 24 hrs and it is still running. When I run a ps command, it only shows the 8 current processes that were created.

How can I find where all the pending ones are running and kill them? I believe I can simply restart Apache/PHP, but I would like to know where these pending processes are and how they can be down or controlled. It seemed originally that the code waited a minute while it executed the above code, then proceeded to the next line of code in the PHP script. So it appears that it created the jobs somewhere and then proceeded to the next line of code.

Is it perhaps something peculiar to the parallel command? Any information is very much appreciated. Thank you.

Solution

The jobs appear to have been produced by a perl process:

perl /usr/bin/parallel -j8 tesseract {...basically the code from the exec() function call in the php script}

perl was invoked either by the gnu parallel command or php's exec function. In any event, htop would not allow killing of process and did not produce any error or status and so it may be a permission problem preventing htop from killing the process. So it was done with sudo on the command line which ultimately killed the process and stopped any further processes creation from the original PHP exec() call.

Answered By - Michael

Answer Checked By - Mary Flores (PHPFixing Volunteer)