It is not head dump (maybe it's your head banging against the wall , it would be heap dump. But a heap dump is not in a dev_serverX file, this would be a thread dump.
Heap dumps can be analyzed with the memory analyser from the link above. This has to be done if you experience outofmemory exceptions and suspect a memory leak.
Thread dumps can be analyzed with solman E2E root cause analyis or with the thread dump viewer -> [SDN search for Thread Dump Viewer|http://www.sdn.sap.com/irj/scn/advancedsearch?query=threaddumpviewer]
Jajajajaj ...... Of course, my head is banging againts the wall .... sorry.
Thank you for response, but in SDN I found the answer to my problem before your response. I already open the file by means of Solution Manager application.
Heap dump --> .hprof files.
I didn't know that dev_server files are named thread dump. Thank you again ...