Hi, I've an online judge system where i take the source code submitted by an user and compile it to an executable and then run it against a predetermined input to produce an output which is checked against a predetermined output. This determines the results as Correct, Wrong or Compile error. The languages are C,C++,java. Please suggest solutions for the below problems 1) How to tell gcc to stop after the first error. I use both gcc 4.2 and gcc 3.4. I tried -Wfatal-error and -Wfatal-error it says unrecognized option. 2) There are many people who submit code without compiling. If they submit C++ (STL or templates ) code which fails to compile due to some problem, it produces lots of output and it is slow, some take 3 - 5 secs. So that is for each submission. In this way if you make 100 submissions the whole system is slow. How to over come this problem? I tried -fsyntax-only but the difference is not that noticable because after that -fsynax-only i have to recompile. 3) Can this submissions be collected for every 5 secs and then compiled in parallel to produce parallel output. Invoking gcc for each submission is going to be slow ? 4) Can we do anything about gcj ? Java compilation errors take the most time.