From: Eric Wong <normalperson@yhbt.net> To: rack-devel@googlegroups.com Subject: Re: Not cleaning up tempfiles for multipart? Date: Thu, 18 Mar 2010 02:54:09 -0700 [thread overview] Message-ID: <20100318095409.GB15049@dcvr.yhbt.net> (raw) In-Reply-To: <f04d2211003170841o5f97169cy165e0fedb3ebe552@mail.gmail.com> Charles Oliver Nutter <headius@headius.com> wrote: > On Sun, Mar 7, 2010 at 7:12 PM, Eric Wong <normalperson@yhbt.net> wrote: > > I guess this deals with wonky multipart uploads that browsers still > > generate these days[1]. Ugh, yeah, it's nasty... > > The comment below in _call is very important. > > > > > > 1. Ensure all tempfiles created by Rack go into an array in env, > > probably env["rack.tempfiles"]: > > > > tempfile = Tempfile.new("foo") > > (env["rack.tempfiles"] ||= []) << tempfile > > I'm with you so far... > > > 2. Have a middleware wrap everything, including the response body: > > I'm a bit new to the middleware thing. Does this mean everyone would > have to configure middleware on their setups to get this > tempfile-closing behavior? And your comment below...does that mean > there are situations where this wouldn't work? > > Closing and removing tempfiles when they're no longer needed should be > the default behavior, not something you have to configure. It's a bug > to not close and remove them (or at least, a bug to keep creating new > ones and expecting GC to clean everything up eventually). I would expect major frameworks to stick this into the default middleware stack as a convenience, but some users want a more bare-bones Rack stack can still opt out. I see it as needless overhead as the vast majority of HTTP requests do not create tempfiles. I don't make decisions for Rack, though. <snip> > > # the Rack server should call this (when we're the body) > > def close > > tempfiles = env["rack.tempfiles"] > > if tempfiles > > tempfiles.each { |tmp| tmp.close! rescue nil } > > end > > end > > By "the Rack server should call this" do you mean that if the server > doesn't call this, tempfiles Rack creates will not be cleaned up until > GC runs? Yes, a Rack-compliant server should call body.close if it responds to body.close at the end of the response cycle for every individual request. I put this in the wrapped body because body.each {} could be relying on the tempfiles to generate the response. body.close is the absolute last action for any Rack application. > Shouldn't Rack itself be guaranteeing it doesn't leave garbage files around? > > > # wrap the normal application call, saving env > > def _call(env) > > self.env = env > > > > # XXX VERY IMPORTANT: > > # you need to ensure env stays the same throughout the request, > > # some middlewares overwrite/replace it instead of merge!-ing into it > > status, headers, body = app.call(env) > > self.body = body > > [ status, headers, self ] > > end > > end > > Same question as above...can badly-written middleware now cause > tempfiles to linger? Yes, it might be safer to do this before app.call above: env["rack.tempfiles"] ||= [] That way if env gets replaced down the stack, e.g. via: app.call(env.merge("foo.hello" => "world")) # env.merge! would be correct above any use of env["rack.tempfiles"] will still point to the same array. Well, almost... Then again some bad middleware could do: env["rack.tempfiles"] += [ tmp_a, tmp_b ] Instead of what they _should_ do: env["rack.tempfiles"].concat([ tmp_a, tmp_b ]) So yes, discourage future middleware authors from replacing the rack.tempfiles array. -- Eric Wong
next prev parent reply other threads:[~2010-03-18 9:54 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-03-05 14:40 Charles Oliver Nutter 2010-03-05 14:47 ` Charles Oliver Nutter 2010-03-05 14:48 ` Charles Oliver Nutter 2010-03-06 10:20 ` Hongli Lai 2010-03-07 14:25 ` Charles Oliver Nutter 2010-03-06 7:55 ` Eric Wong 2010-03-06 10:25 ` Hongli Lai 2010-03-07 14:34 ` Charles Oliver Nutter 2010-03-08 0:22 ` Eric Wong 2010-03-08 1:12 ` Eric Wong 2010-03-17 15:41 ` Charles Oliver Nutter 2010-03-18 9:54 ` Eric Wong [this message] 2014-01-06 22:45 ` Wojtek Kruszewski 2014-02-11 21:05 ` Eric Wong 2014-03-27 21:40 ` Lenny Marks 2010-03-07 23:53 ` Eric Wong 2010-03-08 11:26 ` Hongli Lai 2010-03-08 11:30 ` Hongli Lai 2010-03-08 14:33 ` Randy Fischer 2010-03-08 14:43 ` Charles Oliver Nutter 2010-03-08 14:49 ` James Tucker 2010-03-17 2:37 ` Eric Wong 2010-03-08 13:22 ` Charles Oliver Nutter 2010-03-08 14:42 ` James Tucker 2010-03-08 17:24 ` Hongli Lai 2010-03-09 7:43 ` Charles Oliver Nutter 2010-03-08 10:05 ` James Tucker 2010-03-07 14:27 ` Charles Oliver Nutter 2010-03-08 0:18 ` Eric Wong 2010-03-08 10:07 ` James Tucker
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