[fpc-pascal] Reusing a TProcess object (issue 19997)

Sven Barth pascaldragon at googlemail.com
Tue Oct 11 17:25:01 CEST 2011

Am 11.10.2011 15:44, schrieb Vincent Snijders:
> Hi,
> Is it allowed to execute a TProcess object more than once? And if yes,
> different command lines be used?
> The reason I ask is issue 19997, each invocation of the compiler in
> Lazarus leaks a process handle and a thread handle on windows. (not
> tested on other OS-es).
> If is it allowed to re-use TProcess object, how can it be done without
> leaking handles?

A quick look at the implementation of TProcess let's me come to the 
conclusion that it's not allowed to reuse TProcess. If you look at 
TProcess.Destroy you'll see that only there "FreeStreams" and 
"CloseProcessHandles" is called. So if you create a new process new 
streams and new handles (on Windows) are created (so you are not only 
leaking handles, but also streams if you use "poUsePipes").

You might be able to workaround this by introducing a descendant of 
TProcess and adding a method "Reset" which calls "CloseProcessHandles" 
and frees the streams (you can't use "FreeStreams", because it's 
private, but the streams are protected).


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