| From: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Cosmic ray hits integerset |
| Date: | 2021-06-22 14:40:26 |
| Message-ID: | 188B9595-FBBB-4283-AB11-1C4DB4B432FF@yandex-team.ru |
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| Lists: | pgsql-hackers |
> 22 июня 2021 г., в 19:21, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> написал(а):
>
> On 2021-Jun-22, Thomas Munro wrote:
>
>> Hi,
>>
>> Here's a curious one-off failure in test_integerset:
>>
>> +ERROR: iterate returned wrong value; got 519985430528, expected 485625692160
>
> Cosmic rays indeed. The base-2 representation of the expected value is
> 111000100010001100011000000000000000000
> and that of the actual value is
> 111100100010001100011000000000000000000
>
> There's a single bit of difference.
I've tried to explain this as not a single-event upset, but integer overflow in 30-bits mode of simple8b somewhere. But found nothing so far. Actual error is in bit 35, and next mode is 60-bit mode.
Looks like cosmic ray to me too.
Best regards, Andrey Borodin.
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