Failed to fork a process error in raspberry pi
lazarus / 1-Linux

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gayathri · 2017-10-11 11:01

Hello All,

I am starting a process using TProcess in raspberry pi. This is done
in a loop. The loop runs successfully for half a day and then stops
with an error 'Failed to fork a process'.
This is the code that I am using:

  command:='sudo /sbin/ip link set __INTERFACE__ up type can bitrate
__BAUDRATE__';
  command := StringReplace(command,'__INTERFACE__',interfacename,[]);
  command := StringReplace(command,'__BAUDRATE__',baudrate,[]);

   AProcess := TProcess.Create(nil);

   AProcess.Options := AProcess.Options + [poWaitOnExit,poUsePipes];
   AProcess.CommandLine:=command;
   Aprocess.Execute;

   if AProcess.ExitStatus=0 then
      Result:=0
   else
      Result:=-1;
   AProcess.Free; 


I have tried adding AProcess.WaitForExit after Aprocess.Execute line
and also tried manually killing the Aprocess using the function
fpKill(AProcess.ProcessID,SIGKILL) or also used this function
fpKill(AProcess.ProcessID,SIGINT).

I have also tried removing poUsePipes option.

None of them is working out and the same error occurs again and again.

Please help me in finding a solution for this problem.
Thanks!

Regards,
Gayathri

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marcov · 2017-10-11 12:33

I've no experience with TProcess and sudo commands, but :

My guess is that first working but then later stopping means that you
leak processes somewhere and hit the process limit. This is probably
because sudo is special.

Some tips:

.commandline is deprecated, use the new style, and specially in this
caseif you have programs that run a commandline for you, like sudo or
sh -c,  it might be that the whole commandline should be in one
argumentavoid pousepipes since you don't need it. Try first executing
a shell (so sh,' -c','sudo ...')
If the problem persist, try to find out which process leaks (sudo or
the child process, or another one spawned by "ip"), and/or use strace.