Earlier today when building something, I decided to run make as $ make -jperhaps out of habit with other programs such as cabal where -j defaults to a reasonable limit.About 20 seconds later, my entire desktop grinds to a halt.  I look for various signs of activity. No fans spin up. The HDD light is a solid green, but I hear no disk activity. Hmmmmm. After 10 minutes of silence, I finally see a response to the first keypress I made ages ago, and I also begin to hear the all too familiar sound of disk thrashing. 20 minutes later of slowly trying to wade my way into a terminal on this unresponsive machine, I caved and used REISUB.At first, I figured an unrelated desktop application must have been the culprit, because I have long since had memory limits placed on interactive bash sessions to prevent me from putting myself into exactly this sort of situation!  But /var/log/syslog tells a different story; the OOM killer left behind some ps dumps which are suspiciously packed with c++ and cc1plus processes!Here is a frequency analysis of one of those dumps:Command          Number of appearances'sh'                    322'c++'                   321'cc1plus'               321'chrome'                 27'make'                   27'bash'                    3all else combined       120So I check the man page for GNU make: (emphasis added)-j [jobs], --jobs[=jobs]          Specifies the number of jobs (commands) to run simultaneously.  If          there is more than one -j option, the last one is  effective.   If          the  -j  option  is given without an argument, make will not limit          the number of jobs that can run simultaneously.I'm reluctant to see if I can reproduce the issue (Doctor, it hurts when I do this...), but the results of investigation so far seem to be a home run: Clearly, make -j and the hundreds of resulting processes must have been the cause of the hang and the disk thrashing.  That said, searching the internet, I can't find much warning against it.  Am I jumping to conclusions?Is make -j as dangerous as it would seem to me?  If so, why on earth is it there, and what can be done to idiot-proof it?
Is `make -j` (with no argument) dangerous?
make;out of memory