Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id B23FC3EE for ; Fri, 21 Aug 2015 19:52:36 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ob0-f177.google.com (mail-ob0-f177.google.com [209.85.214.177]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C576114C for ; Fri, 21 Aug 2015 19:52:35 +0000 (UTC) Received: by obbhe7 with SMTP id he7so67586615obb.0 for ; Fri, 21 Aug 2015 12:52:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=M9+m/IwAaxtatifybnc0DJm6U0dGbQBrOkmB4/GfBNo=; b=DelElXySPw+QHwVYn6dGg86+HapPo+0hDqm8NzTwHSRNu6E5mOqBeEhCxQC35P3bgY 3LSgP7MLIeZn/EseD/yY1jF4Wv9cgc2fPs1413qH0e2qo71PMPeLIX0CcEJafhCOkpjF lFPcJS5M8mz2GGi9iaZnx216hOLpe2sgNxCAsZgKhWwVjPsza4ob8+xYLkAKkobKu8pZ nl5Qjs/oYoyJh9uo1bAuwcO0gQaF6S/ZXCZGV8G+mOWr3ShIp4Un53EuGcPzjZc1MvB6 OB/fx/Kp2sai/a4Dq9RBKd8wTEYZKgYUr4Oj4cpD0Rzv/z0lwzxIIhJYMxgH2u55Xbt1 6SrQ== MIME-Version: 1.0 X-Received: by 10.182.250.137 with SMTP id zc9mr9266050obc.79.1440186755189; Fri, 21 Aug 2015 12:52:35 -0700 (PDT) Received: by 10.202.134.78 with HTTP; Fri, 21 Aug 2015 12:52:35 -0700 (PDT) In-Reply-To: <55D77A7F.40402@mattcorallo.com> References: <55D77A7F.40402@mattcorallo.com> Date: Fri, 21 Aug 2015 12:52:35 -0700 Message-ID: From: Danny Thorpe To: Matt Corallo Content-Type: multipart/alternative; boundary=089e01537b22f41424051dd79b72 X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Proposed new policy for transactions that depend on other unconfirmed transactions X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Aug 2015 19:52:36 -0000 --089e01537b22f41424051dd79b72 Content-Type: text/plain; charset=UTF-8 The limits Alex proposed are generous (bordering on obscene!), but dropping that down to allowing only two levels of chained unconfirmed transactions is too tight. Use case: Brokered asset transfers may require sets of transactions with a dependency tree depth of 3 to be published together. ( N seller txs, 1 broker bridge tx, M buyer txs ) If the originally proposed depth limit of 100 does not provide a sufficient cap on memory consumption or loop/recursion depth, a depth limit of 10 would provide plenty of headroom for this 3 level use case and similar patterns. -Danny On Fri, Aug 21, 2015 at 12:22 PM, Matt Corallo via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > I dont see any problem with such limits. Though, hell, if you limited > entire tx dependency trees (ie transactions and all required unconfirmed > transactions for them) to something like 10 txn, maximum two levels > deep, I also wouldnt have a problem. > > Matt > > On 08/14/15 19:33, Alex Morcos via bitcoin-dev wrote: > > Hi everyone, > > > > > > I'd like to propose a new set of requirements as a policy on when to > > accept new transactions into the mempool and relay them. This policy > > would affect transactions which have as inputs other transactions which > > are not yet confirmed in the blockchain. > > > > The motivation for this policy is 6470 > > which aims to limit the > > size of a mempool. As discussed in that pull > > , > > once the mempool is full a new transaction must be able to pay not only > > for the transaction it would evict, but any dependent transactions that > > would be removed from the mempool as well. In order to make sure this > > is always feasible, I'm proposing 4 new policy limits. > > > > All limits are command line configurable. > > > > The first two limits are required to make sure no chain of transactions > > will be too large for the eviction code to handle: > > > > Max number of descendant txs : No transaction shall be accepted if it > > would cause another transaction in the mempool to have too many > > descendant transactions (all of which would have to be evicted if the > > ancestor transaction was evicted). Default: 1000 > > > > Max descendant size : No transaction shall be accepted if it would cause > > another transaction in the mempool to have the total size of all its > > descendant transactions be too great. Default : maxmempool / 200 = > 2.5MB > > > > The third limit is required to make sure calculating the state required > > for sorting and limiting the mempool and enforcing the first 2 limits is > > computationally feasible: > > > > Max number of ancestor txs: No transaction shall be accepted if it has > > too many ancestor transactions which are not yet confirmed (ie, in the > > mempool). Default: 100 > > > > The fourth limit is required to maintain the pre existing policy goal > > that all transactions in the mempool should be mineable in the next > block. > > > > Max ancestor size: No transaction shall be accepted if the total size of > > all its unconfirmed ancestor transactions is too large. Default: 1MB > > > > (All limits include the transaction itself.) > > > > For reference, these limits would have affected less than 2% of > > transactions entering the mempool in April or May of this year. During > > the period of 7/6 through 7/14, while the network was under stress test, > > as many as 25% of the transactions would have been affected. > > > > The code to implement the descendant package tracking and new policy > > limits can be found in 6557 > > which is built off of > 6470. > > > > Thanks, > > Alex > > > > > > > > _______________________________________________ > > bitcoin-dev mailing list > > bitcoin-dev@lists.linuxfoundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --089e01537b22f41424051dd79b72 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
The limits Alex proposed are generous (bordering on obscen= e!), but dropping that down to allowing only two levels of chained unconfir= med transactions is too tight. =C2=A0

Use case: Brokered= asset transfers may require sets of transactions with a dependency tree de= pth of 3 to be published together. ( N seller txs, 1 broker bridge tx, M bu= yer txs )

If the originally proposed depth limit o= f 100 does not provide a sufficient cap on memory consumption or loop/recur= sion depth, a depth limit of 10 would provide plenty of headroom for this 3= level use case and similar patterns.

-Danny
=

On Fri, Aug= 21, 2015 at 12:22 PM, Matt Corallo via bitcoin-dev <<= a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">b= itcoin-dev@lists.linuxfoundation.org> wrote:
I dont see any problem with such limits. Though, hell, if= you limited
entire tx dependency trees (ie transactions and all required unconfirmed transactions for them) to something like 10 txn, maximum two levels
deep, I also wouldnt have a problem.

Matt

On 08/14/15 19:33, Alex Morcos via bitcoin-dev wrote:
> Hi everyone,
>
>
> I'd like to propose a new set of requirements as a policy on when = to
> accept new transactions into the mempool and relay them.=C2=A0 This po= licy
> would affect transactions which have as inputs other transactions whic= h
> are not yet confirmed in the blockchain.
>
> The motivation for this policy is 6470
> <https://github.com/bitcoin/bitcoin/pull/6470> which aims to limit the
> size of a mempool.=C2=A0 As discussed in that pull
> <https://github.com/bitco= in/bitcoin/pull/6470#issuecomment-125324736>,
> once the mempool is full a new transaction must be able to pay not onl= y
> for the transaction it would evict, but any dependent transactions tha= t
> would be removed from the mempool as well.=C2=A0 In order to make sure= this
> is always feasible, I'm proposing 4 new policy limits.
>
> All limits are command line configurable.
>
> The first two limits are required to make sure no chain of transaction= s
> will be too large for the eviction code to handle:
>
> Max number of descendant txs : No transaction shall be accepted if it<= br> > would cause another transaction in the mempool to have too many
> descendant transactions (all of which would have to be evicted if the<= br> > ancestor transaction was evicted).=C2=A0 Default: 1000
>
> Max descendant size : No transaction shall be accepted if it would cau= se
> another transaction in the mempool to have the total size of all its > descendant transactions be too great.=C2=A0 Default : maxmempool / 200= =C2=A0 =3D=C2=A0 2.5MB
>
> The third limit is required to make sure calculating the state require= d
> for sorting and limiting the mempool and enforcing the first 2 limits = is
> computationally feasible:
>
> Max number of ancestor txs:=C2=A0 No transaction shall be accepted if = it has
> too many ancestor transactions which are not yet confirmed (ie, in the=
> mempool). Default: 100
>
> The fourth limit is required to maintain the pre existing policy goal<= br> > that all transactions in the mempool should be mineable in the next bl= ock.
>
> Max ancestor size: No transaction shall be accepted if the total size = of
> all its unconfirmed ancestor transactions is too large.=C2=A0 Default:= 1MB
>
> (All limits include the transaction itself.)
>
> For reference, these limits would have affected less than 2% of
> transactions entering the mempool in April or May of this year.=C2=A0 = During
> the period of 7/6 through 7/14, while the network was under stress tes= t,
> as many as 25% of the transactions would have been affected.
>
> The code to implement the descendant package tracking and new policy > limits can be found in 6557
> <https://github.com/bitcoin/bitcoin/pull/6557> which is built off of 6470.
>
> Thanks,
> Alex
>
>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@l= ists.linuxfoundation.org
> https://lists.linuxfoundation.org= /mailman/listinfo/bitcoin-dev
>
_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.= linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev

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