Submitted by: @pavel-zotov

Attachments:
fb_sort_files_remain_opened_-_test_case.zip

Reproduced on:
LI-T3.0.0.30872
WI-T3.0.0.30855

firebird.conf changes: TempCacheLimit = 64K

DDL: see attach, file CROSS.DDL.
#⁠#⁠#⁠#⁠

Please note that this script contains on-commit trigger with some kind of 'heavy' query to MON$-tables:
-- first check uncommitted data in all other transactions:
if (
exists(
with c as(
select
c.mon$transaction_id tid
--,substring(c.mon$variable_name from 3) vn
,cast( substring(c.mon$variable_name from 3) as varchar(16384)) vn
,min(cast( iif( c.mon$variable_name starting with 'ID_NEW', c.mon$variable_value, null) as int) ) ctx_id_new
,min(cast( iif( c.mon$variable_name starting with 'F1_NEW', c.mon$variable_value, null) as int) ) ctx_f1_new
,min(cast( iif( c.mon$variable_name starting with 'F2_NEW', c.mon$variable_value, null) as int) ) ctx_f2_new
from mon$context_variables c
group by 1,2 -- <<<<<<<<<<<<<<<<<< THIS WILL CAUSE 'SORT' in PLAN <<<<<<<<<<
)
select *
from c ca join c cb
on ca.ctx_id_new<>cb.ctx_id_new
and sign(ca.ctx_f1_new - cb.ctx_f2_new) * sign(cb.ctx_f1_new - ca.ctx_f2_new)>0
) -- exists
)
then
exception ex_crossed_dirty;

Also, note that one of field of that query is deliberately casted to long string (16384 chars).

Test:
1) open *single* isql session that runs script CROSS.SQL - see in attach.
2) wait about 10-15 seconds and than kill that session, e.g. via PSKILL utility (from Sysinternals package).

Result: FB keeps one or two FB_SORT_*-files open infinite time untill restart.

Commits: 462cd99 FirebirdSQL/fbt-repository@c611611