Hi, I just ran into something rather scary: One of my datanode processes that I¹m running with Xmx256M, and a maximum number of Xceiver threads of 4095 had a virtual memory size of over 7GB (!). I know that the VM size on Linux isn¹t necessarily equal to the actual memory used, but I wouldn¹t expect it to be an order of magnitude higher either. I ran pmap on the process, and it showed around 1000 thread stack blocks with roughly 1MB each (which is the default size on the 64bit JDK). The largest block was 3GB in size which I can¹t figure out what it is for.
Does anyone have any insights into this ? Anything that can be done to prevent this other than to restart the DFS regularly ? -- Stefan
