Hello!
When writing some sample code that generates JSON from PostgreSQL, I encountered invalid formatting of UUIDs in JSON. The generated UUID are in truncated form like "0195e993-10". The problem happens under following conditions:
* Generated JSON is fairly large (around 12M in my case, 1.2M almost never happens)
* A lot of connections (40 in my case, for 10 everything was ok)
* Program works for long time (7 minutes almost always errors, 1 minute almost never)
I think the problem is important, as incorrect data is silently returned. It would have been better if postgresql just crashed.
The bug was originally detected in official docker image postgres:17.2, but it still reproduces in postgres:17.4.
Environment:
* Window 10 Pro 22H2
* Docker Engine v27.5.1
* PostgreSQL 17.4 (Debian 17.4-1.pgdg120+2) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
* CPU: 13th Gen Intel(R) Core(TM) i9-13900K 3.00 GHz
* 128M memory
* Java 21 + PG JDBC 42.7.5 (the test application was run from IDEA) - it should not affect the bug, as I just use "rs.getString(1)" to get JSON as java.lang.String.
I do not know the real cause of the bug. PG is a primary suspect, maybe too aggressive optimizations in GCC are used, or here is some memory management error. Possibly, the bug is related to the bugs in 13th Gen Intel CPUs (but in this case more interesting bugs are expected, not just UUIDs).
Best regards, Konstantin Plotnikov
