when debuging a multi-thread program I encounter the error as follows:

*** glibc detected *** /IDC/IDC/idc: double free or corruption (!prev): 0x60079080 ***

and gdb locate it at free().

I run a sample test in which free() is called twice continiously, "*** glibc detected *** /IDC/IDC/idc: double free or corruption (!fasttop): " will be displayed.

when fclose() is called twice continiously,"double free or corruption (!top):" will be displayed.

but what on earth (!prev): is?

thank you very much in advance.

please excuse me for my not good English.

I don't know about !prev but what I do know is that this error just hints to you that one has messed up the dynamic allocation and deallocation of memory. It doesn't tell you anything else. I have encountered glibc double free corruption errors numerous times and everytime they are cryptic messages giving absolutely no clue as to where the error originates, which leaves us looking out every line of code to get to the source of error. So my advice is not delve much into what the glibc error says and check your code dealing with dynamic allocation and de-allocation of memory.

--LUCKY

This kind of error can be difficult to fix. If you don't find the problem soon, then try electric fence or valgrind.

Thank you two for help! I'll check the code line by line carefully to make sure where I messed up with the memory and try to use valgrind.

If I find the reason why (prev!) happen in my code, I'll post it here.