[Libguestfs] [RFC nbdkit PATCH 0/6] Enable full parallel request handling

I want to make my nbd forwarding plugin fully parallel - but to do that, I first need to make nbdkit itself fully parallel ;) With this series, I was finally able to demonstrate out-of-order responses when using qemu-io (which is great at sending back-to-back requests prior to waiting for responses) coupled with the nbd file plugin (which has a great feature of rdelay and wdelay, to make it obvious whether processing occurs in parallel among separate threads or in serial). 'make check' sometimes succeeds with this series, but more often than not I was able to crash or hand on the test-socket-activation test; I've posted another series for the crashes, as well as analysis of the hang. Until the hang is solved, I'm leaving this series as RFC, but review is welcome to see if my approach is sound. Eric Blake (6): connections: Simplify handle_request() connections: Avoid plugin when shutdown is imminent connections: Add read/write lock over client I/O connections: Add thread-safe status indicator connections: Set up thread pool for handling client requests Add --threads option for supporting true parallel requests TODO | 7 -- docs/nbdkit.pod | 12 ++- nbdkit.in | 2 +- plugins/file/file.c | 2 +- src/connections.c | 271 +++++++++++++++++++++++++++++++++++++--------------- src/internal.h | 2 + src/main.c | 20 +++- src/plugins.c | 8 ++ 8 files changed, 237 insertions(+), 87 deletions(-) -- 2.13.6