From: Cory Fields <lists@coryfields•com>
To: Tamas Blummer <tamas@bitsofproof•com>
Cc: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] libconsensus assertion fails if used in multiple threads
Date: Tue, 18 Aug 2015 13:25:39 -0400 [thread overview]
Message-ID: <CAApLimhbZj44OE0HStooCtzW33=jba=eEjf89H=0uJATxAvu5g@mail.gmail.com> (raw)
In-Reply-To: <68E206FF-4ABD-4547-BF73-8661A7C2F08B@bitsofproof.com>
See responses inline.
On Tue, Aug 18, 2015 at 6:31 AM, Tamas Blummer <tamas@bitsofproof•com> wrote:
> Thanks a lot Cory for following through the test case and producing a patch.
>
> I confirm that libconsensus is now running stable within the Bits of Proof
> stack,
> in-line with test cases we use to verify the java implementation of the
> script engine,
> that are BTW borrowed from Bitcoin Core.
>
> The performance of libconsensus is surprisingly close to the java one.
> Validating a 2-of-2 a multi-sig transaction runs at 1021 ops/sec with java
> and 1135 ops/sec
> in libconsensus. This is on a 2.2GH i7 laptop (4 hyper threading cores used
> by 8 threads).
> Another nice demonstration why one should not trade in advances
> of languages for the last decades for a marginal gain of performance with
> C/C++,
> I assume thereby that Bouncy Castle’ EC lib s not superior to OpenSSL's.
A few points there. First, Core is switching to libsecp256k1 for
several reasons, and one of them is speed. I seem to recall it being
up to 8x faster than OpenSSL.
Also, it can depend heavily on compiler switches and optimization
levels. For example, In playing with my test-case for hitting the
OpenSSL race issue, I managed to get a ~100% speedup by simply using
-O3 and lto.
>
> I disagree that the problem was rare in the real-world, it should affect any
> modern
> implementation that validates transactions parallel in multiple threads.
>
Well I'd say you're a bit biased in this case ;)
It's only those using ancient (0.98 or 1.00) versions of OpenSSL who
are affected, or those with OPENSSL_BN_ASM_MONT support disabled or
missing. Note that official releases of libbitcoinconsensus are
compiled against a much newer version and shouldn't have any issues.
The earlier patches for locking callbacks should be unnecessary.
> Aborting also does not make the problem less severe in my opinion.
Well it's not a good thing by any means, but it's certainly better
than incorrect results! In any undefined/error condition for the
consensus library, aborting is the right thing to do. If we can't
explain how we've reached a certain "unreachable" condition as is the
case here, the only reasonable recourse is to shut down. Otherwise we
risk network forks, DOS, etc.
> Therefore hope the pull will be included into Core with next release.
>
It will likely be unnecessary for the next release, but I do think
it's worth backporting to the 0.10 and 0.9 series.
> I can’t assign a timeline to “near future" secp256k1 integration. Can you?
I believe the libsecp256k1 guys are generally happy with the lib these
days, but I'll avoid guessing at a timeline. We can discuss that on
the PR for this fix, which I'll do today.
Regards,
Cory
next prev parent reply other threads:[~2015-08-18 17:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-14 9:59 [bitcoin-dev] Adjusted difficulty depending on relative blocksize Jakob Rönnbäck
2015-08-14 13:32 ` Angel Leon
2015-08-14 14:19 ` Jakob Rönnbäck
2015-08-14 16:37 ` [bitcoin-dev] libconsensus assertion fails if used in multiple threads Tamas Blummer
2015-08-14 21:10 ` Cory Fields
2015-08-18 5:03 ` Cory Fields
2015-08-18 10:31 ` Tamas Blummer
2015-08-18 17:25 ` Cory Fields [this message]
2015-08-18 17:50 ` Cory Fields
2015-08-18 21:40 ` Eric Voskuil
2015-08-14 14:20 ` [bitcoin-dev] Adjusted difficulty depending on relative blocksize Anthony Towns
[not found] ` <A6B32C22-4006-434E-9B89-D7C99B5743A8@me.com>
2015-08-14 14:48 ` Jakob Rönnbäck
2015-08-14 15:00 ` Anthony Towns
2015-08-14 15:03 ` Adam Back
2015-08-14 15:14 ` Jakob Rönnbäck
2015-09-09 3:27 ` Tom Harding
2015-09-09 18:59 ` Warren Togami Jr.
2015-09-09 19:53 ` Tom Harding
2015-08-14 22:12 ` Tom Harding
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