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Created attachment 1295144 [details]
screenshot of top and python

Description of problem:
gc of python that comes with RHEL7.3 does not collect all memory it allocates

Version-Release number of selected component (if applicable):
Red Hat Enterprise Linux Server release 7.3 (Maipo)
Linux localhost.localdomain 3.10.0-514.26.2.el7.x86_64 #1 SMP Fri Jun 30 05:26:04 UTC 2017 x86_64 x86_
Python 2.7.5 (default, Aug  2 2016, 04:20:16)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux2

How reproducible:
d = [ {'sdfdfsdfsfef': 1} for x in xrange(10000000)]
del d
import gc; gc.collect()

Steps to Reproduce:
1. Open python on RHEL7 and enter following python code
2. d = [ {'sdfdfsdfsfef': 1} for x in xrange(10000000)]
3. del d
4. import gc; gc.collect()
5. Run top or ps to get memory allocation of the process

Actual results:
The process still uses 2.4 GB of Memory

Expected results:
Mem usage less than 100KB

Additional info:

I plan to look into this in the RHEL 7.5 devel phase.

Note that the memory is not leaked; it is only not "returned" to the OS; subsequent allocations will re-use the memory.

That being said, this was fixed upstream (in Python 3.3 and 2.7.7) by using mmap() to allocate arenas and using pre-allocated pools for dicts. From an engineering POV, backporting the patch shouldn't be difficult.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0833