pytest-dev / pytest-dev/execnet
Group.__init() should be parallelised
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Description
- Bitbucket: https://bitbucket.org/hpk42/execnet/issue/28
- Originally reported by: @crusaderky
- Originally created at: 2014-01-22T16:51:21.959
Consider the following snippet:
hosts = [...list of hosts...]
group = execnet.Group(("ssh %s" % host for host in hosts))
group.remote_exec(something)
Imagine having a grid of 200 hosts.
While Group.remote_exec() will run on all the hosts in parallel, Group.__init__() will connect via ssh to each one of them, serially. On a typical LAN, this easily accounts to minutes.
I attach a patch for multi.py (on top of the latest hg commit) that is intended to fix the problem. However, with that patch the program deadlocks in gateway_base.py, line 360, and I can't figure out the reason.
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Research direction
Start in multi.py at Group.init and inspect gateway_base.py around line 360, where the reported patch deadlocks. Reproduce initialization with many SSH gateways and compare behavior with the attached patch. Done means Group initialization connects to hosts in parallel without deadlocking, while Group.remote_exec() continues to work.
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Assessment
- Tech stack
- python
- Domain
- distributed-systems
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100