Re: PATCH: pgbench - remove thread fork-emulation

On 04/28/2015 02:18 AM, Fabien COELHO wrote:
> This patch removes the pgbench thread fork-emulation code and simplifies
> things where possible, especially around pthread_create and pthread_join.
> The stats collection for the report is done directly instead of using an
> intermediate structure.
>
> As a result, if no thread implementation is available, pgbench is
> restricted to work with only the main thread (ie "pgbench -j 1 ...").
>
>
> == Rational ==
>
> Pgbench currently provides a thread emulation through process forks. This
> feature was developed way back when it may have been common that some
> platforms were not supporting threads. This is now very rare (can you name
> one such platform?).
>
> However, the thread fork-emulation feature has drawbacks: Namely,
> processes are not threads, the memory is not shared (sure), so it hinders
> simple implementation for some features, or results in not providing these
> features with fork-emulation, or having a different behavior under
> fork-emulation:
>
> Latency collection (-r) is not supported with fork emulation.
>
> Progress (-P) is reported differently with fork emulation.
>
> For a new feature under discussion, which consist in allowing one log
> instead of per-thread logs, supporting fork-emulation requires a (heavy)
> post-processing external sort phase whereas with actual threads all
> threads can share and append to the same log file with limited overhead,
> which is significantly simpler.

I agree with all that, it's time to let the fork-emulation mode to go.
Committed.

- Heikki