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Possible memory leak with enumerated table dump?

Flying
New Contributor III

I have the following code fragment:

E:\test>q
KDB+ 3.6 2019.04.02 Copyright (C) 1993-2019 Kx Systems
w32/ 8()core 4095MB xxxxxxxx xxxxxxxx xxx.xxx.xxx.xxx NONEXPIRE

Welcome to kdb+ 32bit edition
For support please see http://groups.google.com/d/forum/personal-kdbplus
Tutorials can be found at http://code.kx.com
To exit, type \\
To remove this startup msg, edit q.q
q)Syms:([A:`$/:"c"$(`int$"A")+til 26] NS:til 26)
q)T:{ ([] A:`Syms$upper x?`1; B:-1+x?2.; C:x?1000) };
q)(persist:`:T.dat) set T 10000;
q).Q.w[]
used| 304208
heap| 67108864
peak| 67108864
wmax| 0
mmap| 0
mphy| 4294967295
syms| 668
symw| 24354
q)get persist
A B           C
-----------------
L 0.1561184   314
..
q).Q.w[]
used| 370736
heap| 67108864
peak| 67108864
wmax| 0
mmap| 0
mphy| 4294967295
syms| 668
symw| 24354
q)do[1000; get persist ];
q).Q.w[]
used| 65906736
heap| 134217728
peak| 134217728
wmax| 0
mmap| 0
mphy| 4294967295
syms| 668
symw| 24354
q).Q.gc[]
0

As seen from above, the "used" space as reported by `Q.w[] keeps increasing every single time `:T.dat file was read.

Is this a sign of a memory leak somewhere caused by the enumerated column A in T.dat?

2 REPLIES 2

rocuinneagain
Valued Contributor
Valued Contributor

I tested this in 3.6 2019.04.02 could reproduce it.

The issue is not present in 3.6 2020.05.04. 

Release notes of fix:

2019.05.24
FIX
reading enums in log format could leak memory. e.g.
q)h:hopen`:a set ();h enlist(`u;`sym?`a`b`c);hclose h;do[5;get`:a;0N!.Q.w[]`used]

 

Flying
New Contributor III

Thanks for pointing this out. 2020.05.04 seems good. But I don't seem to be able to find a 32-bit q for this version. (My test environment, unfortunately, depends on a couple of 32-bit DLLs. So I had to find a 32-bit q to use.) Any luck that I can find a 32-bit build of 2020.05.04 (or newer) anywhere?