Thanks to you all for inspiration.<br><br>My web app (which otherwise ran ok) was getting stuck while getting harassed by ab (apache-benchmark) after receiving some 800+ requests in short succession (not less, never gotten to 900, what was weird that running like 500 reqs - pause - 500 reqs ... went ok).<br>
<br>After compiling with -threaded and running with +RTS -N2 it handles 10k+ requests (with 10 concurrent request running at once) without missing a beat.<br><br>Well, at least I double checked everything else ;-)))<br>