[DRILL-4278] Memory leak when using LIMIT

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4.0, 1.5.0
• Fix Version/s: 1.5.0
• Component/s: Execution - RPC

Environment

OS X

0: jdbc:drill:zk=local> select * from sys.version;
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

version

commit_id

commit_message

commit_time

build_email

build_time

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

1.4.0

32b871b24c7b69f59a1d2e70f444eed6e599e825

[maven-release-plugin] prepare release drill-1.4.0

08.12.2015 @ 00:24:59 PST

[e-mail]

08.12.2015 @ 01:14:39 PST

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

0: jdbc:drill:zk=local> select * from sys.options where status <> 'DEFAULT';
---------------------------------------------------------------------------------------+

name

kind

type

status

num_val

string_val

bool_val

float_val

---------------------------------------------------------------------------------------+

planner.slice_target	LONG	SYSTEM	CHANGED	10	null	null	null
planner.width.max_per_node	LONG	SYSTEM	CHANGED	5	null	null	null

---------------------------------------------------------------------------------------+
2 rows selected (0.16 seconds)

• Assignee: Jacques Nadeau
• Reporter: jean-claude
• Reviewer: Victoria Markman
• Created: 16/Jan/16 05:58
• Updated: 02/Feb/16 00:49
• Resolved: 20/Jan/16 15:32

Description

copy the parquet files in the samples directory so that you have a 12 or so
$ ls -lha /apache-drill-1.4.0/sample-data/nationsMF/
nationsMF1.parquet
nationsMF2.parquet
nationsMF3.parquet

create a file with a few thousand lines like these
select * from dfs.`/Users/jccote/apache-drill-1.4.0/sample-data/nationsMF` limit 500;

start drill
$ /apache-drill-1.4.0/bin/drill-embeded

reduce the slice target size to force drill to use multiple fragment/threads
jdbc:drill:zk=local> system set planner.slice_target=10;

now run the list of queries from the file your created above
jdbc:drill:zk=local> !run /Users/jccote/test-memory-leak-using-limit.sql

the java heap space keeps going up until the old space is at 100% and eventually you get an OutOfMemoryException in drill

$ jstat -gccause 86850 5s
S0 S1 E O M CCS YGC YGCT FGC FGCT GCT LGCC GCC
0.00 0.00 100.00 100.00 98.56 96.71 2279 26.682 240 458.139 484.821 GCLocker Initiated GC Ergonomics
0.00 0.00 100.00 99.99 98.56 96.71 2279 26.682 242 461.347 488.028 Allocation Failure Ergonomics
0.00 0.00 100.00 99.99 98.56 96.71 2279 26.682 245 466.630 493.311 Allocation Failure Ergonomics
0.00 0.00 100.00 99.99 98.56 96.71 2279 26.682 247 470.020 496.702 Allocation Failure Ergonomics

If you do the same test but do not use the LIMIT then the memory usage does not go up.

If you add a where clause so that no results are returned, then the memory usage does not go up.

Something with the RPC layer?

Also it seems sensitive to the number of fragments/threads. If you limit it to one fragment/thread the memory usage goes up much slower.

I have used parquet files and CSV files. In either case the behaviour is the same.