Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1R0x0l-0004pQ-He for bitcoin-development@lists.sourceforge.net; Tue, 06 Sep 2011 14:52:27 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.220.175 as permitted sender) client-ip=209.85.220.175; envelope-from=mh.in.england@gmail.com; helo=mail-vx0-f175.google.com; Received: from mail-vx0-f175.google.com ([209.85.220.175]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1R0x0k-0002eE-BU for bitcoin-development@lists.sourceforge.net; Tue, 06 Sep 2011 14:52:27 +0000 Received: by vxj14 with SMTP id 14so6390856vxj.34 for ; Tue, 06 Sep 2011 07:52:21 -0700 (PDT) MIME-Version: 1.0 Received: by 10.52.38.99 with SMTP id f3mr5094454vdk.392.1315320740917; Tue, 06 Sep 2011 07:52:20 -0700 (PDT) Sender: mh.in.england@gmail.com Received: by 10.52.157.228 with HTTP; Tue, 6 Sep 2011 07:52:20 -0700 (PDT) In-Reply-To: <4E662B79.5090303@gmail.com> References: <4E65CEE6.7030002@gmail.com> <4E65DA06.9060403@gmail.com> <4E661FAE.9020008@gmail.com> <4E662B79.5090303@gmail.com> Date: Tue, 6 Sep 2011 16:52:20 +0200 X-Google-Sender-Auth: c6m0gMk9rEmJGa5GUVVFFVJN6zg Message-ID: From: Mike Hearn To: shadders.del@gmail.com Content-Type: multipart/alternative; boundary=bcaec51d2780872fd304ac46f916 X-Spam-Score: -0.7 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (mh.in.england[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.0 HTML_MESSAGE BODY: HTML included in message 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 T_TO_NO_BRKTS_FREEMAIL To: misformatted and free email service -0.3 AWL AWL: From: address is in the auto white-list X-Headers-End: 1R0x0k-0002eE-BU Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Building a node crawler to map network X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 Sep 2011 14:52:27 -0000 --bcaec51d2780872fd304ac46f916 Content-Type: text/plain; charset=UTF-8 On Tue, Sep 6, 2011 at 4:17 PM, Steve wrote: > ** > I'm not really understanding the use case though. I believe most > bitcoind's have a default max connections of 8. Is the goal to increase > this without fundamentally altering the bitcoind concurrency model? > bitcoind already uses asynchronous IO. That's not the problem. The issue came up in a conversation about scalability. If Bitcoins popularity continues to grow, users are very likely to migrate away from running full verifying nodes to lightweight clients, either a different mode of the Satoshi client or different implementations like the Android Wallet or MultiBit. Lightweight clients cannot verify thus should not relay. And they'll be run by users who just want to send/receive coins from time to time, so don't leave the programs running 24/7. The result could be running out of sockets (like we have had problems with recently). It's especially true because lightweight clients cannot check transactions for themselves. If they want to show transactions appearing immediately (and they do), they have to use "heard from lots of nodes" as a proxy for validity. So lightweight clients are likely to be socket intensive. We could solve this by just hoping that lots of people run full nodes. The problem is that a full node is quite an intensive thing already, it uses lots of CPU and disk seeks, and will just get more expensive in future. And as transaction traffic increases, that leaves less CPU time available to service thousands of connected clients. The ROI of bringing up a new node decreases at the same time as the userbase increases. One traditional approach to solving this is frontend proxies. Jabber.com/org used this technique many years ago, and Google has also used it to scale up the lockservice (see section 3.1). It's effective because often maintaining connections to thousands of clients doesn't involve much brainwork, just shifting bytes around. This is especially true of Bitcoin. So if somebody is running a full node already they could increase their client capacity by just bringing up a frontend proxy and having it handle things like outbound tx broadcasts/deduping inbound broadcasts, connection setup, relaying recently found blocks etc. A well written proxy could probably support tens of thousands of simultaneous clients which frees up the bitcoinds time for verification and wallet manipulation. --bcaec51d2780872fd304ac46f916 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Tue, Sep 6, 2011 at 4:17 PM, Steve <shadders.del@gmail.c= om> wrote:
=20 =20 =20
I'm not really understandin= g the use case though.=C2=A0 I believe most bitcoind's have a default max connections of 8.=C2=A0 Is the goal t= o increase this without fundamentally altering the bitcoind concurrency model?

bitcoind alrea= dy uses asynchronous IO. That's not the problem.

The issue came up in a conversation about scalability. If Bitcoins popul= arity continues to grow, users are very likely to migrate away from running= full verifying nodes to lightweight clients, either a different mode of th= e Satoshi client or different implementations like the Android Wallet or Mu= ltiBit.

Lightweight clients cannot verify thus should not relay= . And they'll be run by users who just want to send/receive coins from = time to time, so don't leave the programs running 24/7. The result coul= d be running out of sockets (like we have had problems with recently). It&#= 39;s especially true because lightweight clients cannot check transactions = for themselves. If they want to show transactions appearing immediately (an= d they do), they have to use "heard from lots of nodes" as a prox= y for validity. So lightweight clients are likely to be socket intensive.

We could solve this by just hoping that lots of people = run full nodes. The problem is that a full node is quite an intensive thing= already, it uses lots of CPU and disk seeks, and will just get more expens= ive in future. And as transaction traffic increases, that leaves less CPU t= ime available to service thousands of connected clients. The ROI of bringin= g up a new node decreases at the same time as the userbase increases.

One traditional approach to solving this is frontend pr= oxies. Jabber.com/org used this technique many years ago, and Google has al= so used it to scale up = the lockservice=C2=A0(see section 3.1). It's effective because ofte= n maintaining connections to thousands of clients doesn't involve much = brainwork, just shifting bytes around. This is especially true of Bitcoin. = So if somebody is running a full node already they could increase their cli= ent capacity by just bringing up a frontend proxy and having it handle thin= gs like outbound tx broadcasts/deduping inbound broadcasts, connection setu= p, relaying recently found blocks etc. A well written proxy could probably = support tens of thousands of simultaneous clients which frees up the bitcoi= nds time for verification and wallet manipulation.
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