From: Jeff Garzik <jgarzik@bitpay•com>
To: Gavin Andresen <gavinandresen@gmail•com>
Cc: "bitcoin-development@lists•sourceforge.net"
<bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] bitcoind stops responding
Date: Fri, 4 Oct 2013 11:05:29 -0400 [thread overview]
Message-ID: <CAJHLa0NP4f9i-fUQfCh_RQCn3zpih9y0mT8kSXeoOk4hT0Twbg@mail.gmail.com> (raw)
In-Reply-To: <CABsx9T2OvOs9ijj8kk4ZdBT5u-2Bb3rYG0AZtk3FFDWi+H_oHw@mail.gmail.com>
On Fri, Oct 4, 2013 at 2:22 AM, Gavin Andresen <gavinandresen@gmail•com> wrote:
> RE: running into the maximum-of-4-keepalive-requests : simple workaround is
> to run with -rpcthreads=11 (or however many keepalive connections you need
> to support). I agree that the rpc code should be smarter; making the last
> rpc thread ignore keepalive and always disconnecting should be a fairly
> simple patch, and "patches welcome."
It's all still working around a problem unchanged since Satoshi wrote
it: the HTTP server code paths use blocking I/O.
Amusingly, we do this through an async I/O library, which helps
facilitate SSL, but all our connections and operations are blocking.
That's why RPC was multi-threaded in part: to work around the ugly
blocking nature of the code. At least with multiple threads, one
thread will not stall another even if the network stalls (or a
software bug triggers a stall etc.)
Hopefully I can dive into the code and make is truly async I/O. It
takes some work, and I'm happy if someone else steals the task, but
that's what really needs to be done.
I tried the multi-threaded approach, writing an entire boost::asio
skeleton JSON-RPC HTTP server: https://github.com/jgarzik/rpcsrv
This is working, tested code that uses boost::asio properly. It's
also quite a bit of LOC, and a bit messy to boot (four LOC per boost
async action and incomprehensible compiler errors in return for proper
async+MT).
A single thread with async I/O is likely sufficient for even heavy
uses of RPC -- since today it all goes through a big lock anyway.
--
Jeff Garzik
Senior Software Engineer and open source evangelist
BitPay, Inc. https://bitpay.com/
next prev parent reply other threads:[~2013-10-04 15:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-30 20:44 slush
2013-09-30 21:01 ` Warren Togami Jr.
2013-09-30 22:00 ` Fatima Castiglione Maldonado 发
2013-09-30 22:08 ` Gregory Maxwell
2013-10-01 0:05 ` Fatima Castiglione Maldonado 发
2013-10-01 1:26 ` Jeff Garzik
2013-10-01 0:20 ` Chris Double
2013-10-01 1:17 ` Jeff Garzik
2013-10-01 8:58 ` slush
2013-10-04 6:22 ` Gavin Andresen
2013-10-04 15:05 ` Jeff Garzik [this message]
2013-10-01 4:03 ` Olivier Langlois
2013-10-01 7:10 ` Olivier Langlois
2013-10-01 14:17 ` Jeff Garzik
2013-10-02 3:20 ` Olivier Langlois
2013-10-04 3:52 ` Olivier Langlois
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