On Thu Apr 22 14:45:38 EDT 2010, st...@quintile.net wrote: > replica uses fcp which works multithreaded for speed. > > Perhaps the implementation of fswrite() #Z in 9vx uses a seek() > followed by a write() rather than pwrite() which is not thread safe.
replica actually uses replica/applylog.c:^/worker internally, not fcp. but essentially, it's the same thing. it copies NBUF=8192 bytes at a time with 16 parallel processes. #Z uses pwrite on non-sockets. in theory, since NBUF < SSIZE_MAX, pwrite should be atomic to normal files. you're not using a fuse-based fs, are you? possible ways to debug: 1. reduce NBUF to PIPE_BUF=4096. guard against someone treating the fd as a pipe. 2. put a qlock in the UnixFd structure in devfs-posix.c. lock for all io. - erik
