Andrew Schwartzmeyer created MESOS-8668:
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Summary: Transition libprocess on Windows to use the Thread Pool
API
Key: MESOS-8668
URL: https://issues.apache.org/jira/browse/MESOS-8668
Project: Mesos
Issue Type: Epic
Components: libprocess
Environment: Windows 10
Reporter: Andrew Schwartzmeyer
This epic covers the work necessary to use the Windows [Thread Pool
API|https://msdn.microsoft.com/en-us/library/windows/desktop/ms686766(v=vs.85).aspx]
instead of libev or libevent on Windows.
The design of libprocess closely mimics the built-in Thread Pool API, using I/O
Completion Ports for asynchronous I/O. It makes sense to use this API because
the semantics of libprocess map 1-1 to the Windows async asynchronous support.
Transitioning to IOCP is necessary to implement non-blocking pipes, as the
existing eventing libraries (e.g. libevent) only implement asynchronous sockets
on Windows; but there are many instances of Mesos requiring asynchronous pipes
too. As such, the existing use of libevent is fundamentally broken.
Specifically, this was first discovered in test
{{HungDockerTest.ROOT_DOCKER_InspectHungDuringPull}}, but is also evidenced
through {{IOTest.Read}} and others which use non-blocking pipes.
The alternative eventing libraries libev and libuv were considered, but we are
choosing not to use them as they do not implement non-blocking pipes
sufficiently for Windows. libev is not easy to build on Windows, and does not
support IOCP. While libevent uses IOCP for reading and writing sockets, it uses
{{select()}} to detect and dispatch events (which results in poor performance),
and does not use support IOCP for pipes. libuv claims to support IOCP on
Windows, but they do not support [named
pipes|https://github.com/libuv/libuv/issues/1688] and only supportes
[synchronous pipes|https://github.com/libuv/libuv/issues/95]. Moreover, it is
simpler to use the Thread Pool API in libprocess directly, instead of using a
library to abstract over that API, as libprocess already provides the
abstraction we're seeking for Mesos.
Additionally, by using the built-in Windows IOCP support, we can eventually
support SSL using the Windows crypto libraries, instead of requiring OpenSSL on
Windows (the current case for libprocess).
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