From: Ryan Johnson <ryan.johnson@cs.utoronto.ca>
To: Reza Taheri <rtaheri@vmware.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: High rate of transaction failure with the Serializable Isolation Level
Date: Sat, 26 Jul 2014 19:51:03 -0400
Message-ID: <53D43EE7.4000500@cs.utoronto.ca> (raw)
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That does sound pretty similar, modulo the raw performance difference. I
have no idea how many MEE threads there were; it was just a quick run
with exactly zero tuning, so I use whatever dbt5 does out of the box.
Actually, though, if you have any general tuning tips for TPC-E I'd be
interested to learn them (PM if that's off topic for this discussion).
Regards,
Ryan
On 26/07/2014 7:33 PM, Reza Taheri wrote:
> Hi Ryan,
> Thanks a lot for sharing this. When I run with 12 CE threads and 3-5 MEE threads (how many MEE threads do you have?) @ 80-90 tps, I get something in the 20-30% of trade-result transactions rolled back depending on how I count. E.g., in a 5.5-minute run with 3 MEE threads, I saw 87.5 tps. There were 29200 successful trade-result transactions. Of these, 5800 were rolled back, some more than once for a total of 8450 rollbacks. So I'd say your results and ours tell similar stories!
>
> Thanks,
> Reza
>
>> -----Original Message-----
>> From: pgsql-performance-owner@postgresql.org [mailto:pgsql-
>> performance-owner@postgresql.org] On Behalf Of Ryan Johnson
>> Sent: Saturday, July 26, 2014 2:06 PM
>> To: Reza Taheri
>> Cc: pgsql-performance@postgresql.org
>> Subject: Re: High rate of transaction failure with the Serializable Isolation
>> Level
>>
>> Dredging through some old run logs, 12 dbt-5 clients gave the following when
>> everything was run under SSI (fully serializable, even the transactions that
>> allow repeatable read isolation). Not sure how that translates to your results.
>> Abort rates were admittedly rather high, though perhaps lower than what
>> you report.
>>
>> Transaction % Average: 90th % Total Rollbacks % Warning Invalid
>> ----------------- ------- --------------- ------- -------------- ------- -------
>> Trade Result 5.568 0.022: 0.056 2118 417 19.69% 0 91
>> Broker Volume 5.097 0.009: 0.014 1557 0 0.00% 0 0
>> Customer Position 13.530 0.016: 0.034 4134 1 0.02% 0 0
>> Market Feed 0.547 0.033: 0.065 212 45 21.23% 0 69
>> Market Watch 18.604 0.031: 0.061 5683 0 0.00% 0 0
>> Security Detail 14.462 0.015: 0.020 4418 0 0.00% 0 0
>> Trade Lookup 8.325 0.059: 0.146 2543 0 0.00% 432 0
>> Trade Order 9.110 0.006: 0.008 3227 444 13.76% 0 0
>> Trade Status 19.795 0.030: 0.046 6047 0 0.00% 0 0
>> Trade Update 1.990 0.064: 0.145 608 0 0.00% 432 0
>> Data Maintenance N/A 0.012: 0.012 1 0 0.00% 0 0
>> ----------------- ------- --------------- ------- -------------- ------- -------
>> 28.35 trade-result transactions per second (trtps)
>>
>> Regards,
>> Ryan
>>
>> On 26/07/2014 3:55 PM, Reza Taheri wrote:
>>> Hi Ryan,
>>> That's a very good point. We are looking at dbt5. One question: what
>> throughput rate, and how many threads of execution did you use for dbt5?
>> The failure rates I reported were at ~120 tps with 15 trade-result threads.
>>> Thanks,
>>> Reza
>>>
>>>> -----Original Message-----
>>>> From: pgsql-performance-owner@postgresql.org [mailto:pgsql-
>>>> performance-owner@postgresql.org] On Behalf Of Ryan Johnson
>>>> Sent: Friday, July 25, 2014 2:36 PM
>>>> To: pgsql-performance@postgresql.org
>>>> Subject: Re: High rate of transaction failure with the Serializable
>>>> Isolation Level
>>>>
>>>> On 25/07/2014 2:58 PM, Reza Taheri wrote:
>>>>> Hi Craig,
>>>>>
>>>>>> According to the attached SQL, each frame is a separate phase in
>>>>>> the
>>>> operation and performs many different operations.
>>>>>> There's a *lot* going on here, so identifying possible
>>>>>> interdependencies isn't something I can do in a ten minute skim
>>>>>> read over
>>>> my morning coffee.
>>>>> You didn't think I was going to bug you all with a trivial problem,
>>>>> did you? :-) :-)
>>>>>
>>>>> Yes, I am going to have to take an axe to the code and see what pops
>> out.
>>>> Just to put this in perspective, the transaction flow and its
>>>> statements are borrowed verbatim from the TPC-E benchmark. There
>> have
>>>> been dozens of TPC-E disclosures with MS SQL Server, and there are
>>>> Oracle and DB2 kits that, although not used in public disclosures for
>>>> various non-technical reasons, are used internally in by the DB and
>>>> server companies. These 3 products, and perhaps more, were used
>> extensively in the prototyping phase of TPC-E.
>>>>> So, my hope is that if there is a "previously unidentified
>>>>> interdependency
>>>> between transactions" as you point out, it will be due to a mistake
>>>> we made in coding this for PGSQL. Otherwise, we will have a hard time
>>>> convincing all the council member companies that we need to change
>>>> the schema or the business logic to make the kit work with PGSQL.
>>>>> Just pointing out my uphill battle!!
>>>> You might compare against dbt-5 [1], just to see if the same problem
>>>> occurs. I didn't notice such high abort rates when I ran that
>>>> workload a few weeks ago. Just make sure to use the latest commit,
>>>> because the "released" version has fatal bugs.
>>>>
>>>> [1]
>>>>
>> https://urldefense.proofpoint.com/v1/url?u=https://github.com/peterge
>>>> og
>> hegan/dbt5&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=b9TKmA0CPjr
>> oD2HLPTHU27nI9PJr8wgKO2rU9QZyZZU%3D%0A&m=6E%2F9fWJPMGjpMyP
>> xtY0nsamLLW%2FNsTXu7FP9Wzauj10%3D%0A&s=b3f269216d419410f3f07bb
>>>> 774a27b7d377744c9d423df52a3e62324d9279958
>>>>
>>>> Ryan
>>>>
>>>>
>>>>
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To: pgsql-performance@postgresql.org
Cc: ryan.johnson@cs.utoronto.ca, rtaheri@vmware.com
Subject: Re: High rate of transaction failure with the Serializable Isolation Level
In-Reply-To: <53D43EE7.4000500@cs.utoronto.ca>
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