On 31.03.2015 18:26, Rowan Collins wrote:
Andrey Hristov wrote on 31/03/2015 16:02:
Currently in MT environment the task of data separation is pushed to
the TSRM by using TLS. Now, if TSRM is reimplemented in a fashion that
the data is not stored by using TLS but other mechanism and
cooperative multitasking is not something that can't be done. The
truth is that userland is isolated from the process data space so for
it it won't make a difference. It's just that using threads for
separation is the easiest thing (after process per script).
The good thing is that TSRM is an abstraction for its clients.
Isn't the point that to get a real advantage from these technologies,
the *userland* needs to be aware of threads / events? That's what
requires a fundamental rethink of the language.
No, actually it doesn't need threads. There is no need to introduce
threads. Threads are for coarsely grained tasks. It is overkill to start
and finish threads in this environment. It is not overkill to have pool
of threads that can execute simple tasks.
PHP doesn't have this problem - the need for threads. PHP's problem are
all the blocking APIs, including the ones I have worked on and created
myself. PHP needs non-blockable APIs + a notion of coroutines +
promises. How the coroutines are scheduled is not important (whether in
the same thread, on thread pool, even in another process). Directly
sharing data should not be possible, only serialized input/output.
TSRM/TLS allows you to drop from one-process-per-request to
one-thread-per-request, but it doesn't save you the expense of
repeatedly building up and tearing down an execution environment.
So, if Zend can be optimized to quickly clean the execution environment,
and easily switch between them, we can have a giant leap towards
concurrent non-blockable PHP. The idea is simple - the Zend environment
should be some structure, and TSRM needs implementation not using TLS,
in this case. The MySQL Server used to bind a connection to a thread but
since years these are decoupled and with the right plugin you can have
100 threads serving many times more connections because thread switching
is an expensive task. This ain't rocket science.
Regards,
Best,
Andrey
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