Nick,
> ZeroMQ crashed today.
>
> This is a Win32 build of both ZMQ and myApp.
> myApp was running fine with several thousand messages, when the memcpy code
> line below threw the following exception.
>
> "Unhandled exception at 0x6404edd6 (msvcr90d.dll) in myApp.exe: 0xC0000005:
> Access violation reading location 0xfeeefeee."
>
> debugging shows the following values:
> - buffer 0x00d9b570 "%" unsigned char *
> pos 2 unsigned int
> + write_pos 0xfeeefeee <Bad Ptr> unsigned char *
> to_copy 8190 unsigned int
>
> looks like a bad pointer.
>
> encoder.hpp
>
> // If there are no data in the buffer yet and we are able to
> // fill whole buffer in a single go, let's use zero-copy.
> // There's no disadvantage to it as we cannot stuck multiple
> // messages into the buffer anyway. Note that subsequent
> // write(s) are non-blocking, thus each single write writes
> // at most SO_SNDBUF bytes at once not depending on how large
> // is the chunk returned from here.
> // As a consequence, large messages being sent won't block
> // other engines running in the same I/O thread for excessive
> // amounts of time.
> if (!pos && !*data_ && to_write >= buffersize) {
> *data_ = write_pos;
> *size_ = to_write;
> write_pos = NULL;
> to_write = 0;
> return;
> }
>
> // Copy data to the buffer. If the buffer is full, return.
> size_t to_copy = std::min (to_write, buffersize - pos);
> =======> memcpy (buffer + pos, write_pos, to_copy);
> pos += to_copy;
> write_pos += to_copy;
> to_write -= to_copy;
> if (pos == buffersize) {
> *data_ = buffer;
> *size_ = pos;
> return;
> }
It looks like a memory overwrite either in 0MQ or the application. Do
you have a test program to reproduce the problem?
> Let me know what the error was so that I can fix it in the trunk.
Have you managed to find out what the error code is?
Martin
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