gdb session: PrimProc (ColumnStore 23.02.24 + MCOL-5950 backport, Drone PR build), during a disk-based GROUP BY
Breakpoint at utils/rowgroup/rowstorage.cpp:1891 (RowAggStorage::dump(), the "if (freeMem > leaveFree)" line); first hit, then detach.
Commands: break rowstorage.cpp:1891 / info locals / print this->fNumOfInputRGPerThread, fMaxRows,
fEnabledDiskAggregation, fAllowGenerations, *this->fMM, leaveFree, freeMem, freeAttempts / detach
(Output below is verbatim except the variable names in parentheses after $1..$8, added for readability.)

Breakpoint 1 at 0x7f1cd44ccce5: file /mdb/verylongdirnameforverystrangecpackbehavior/storage/columnstore/columnstore/utils/rowgroup/rowstorage.cpp, line 1891.
[Switching to Thread 0x7f14630bc700 (LWP 158154)]
HIT tid=93
success = <optimized out>
freeMemLimit = 52428800
leaveFree = 9882185000
freeAttempts = 1
freeMem = 9377971406
spilled = false
totalMem = <optimized out>
$1 = 20        (fNumOfInputRGPerThread)
$2 = 8192      (fMaxRows)
$3 = true      (fEnabledDiskAggregation)
$4 = true      (fAllowGenerations)
$5 = {_vptr.MemManager = 0x7f1cd44fa698 <vtable for rowgroup::RMMemManager+16>, fMemUsed = 33031}
$6 = 9882185000   (leaveFree)
$7 = 9377971406   (freeMem)
$8 = 1            (freeAttempts)
[Inferior 1 (process 157450) detached]

Configuration: TotalUmMemory=18G, AllowDiskBasedAggregation=Y, RowAggrRowGroupsPerThread default (20).