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+++ This bug was initially created as a clone of Bug #1570981 +++ Description of problem: In OCP 3.7, we introduced "temp" tables for raw data in Hawkular Metrics. A different table is used for raw data per every two hour block. After the two hour block has passed, the table is never written to again. The compression job that runs in the Hawkular Metrics server will subsequently fetch the raw data from the table, compress it, write the compressed data to the data_compressed table, and then finally drop the temp table. Handling raw data this way allows space on disk to be reclaimed more quickly, reduces compaction, which in turn reduces I/O and CPU usage. Due to a bug in the job scheduling code in Hawkular Metrics, temp tables were not getting dropped. Hawkular Metrics is supposed to maintain a days worth of tables as a bit of a buffer to ensure that there is always a table to which to write. At any given time there should be 13 or 14 temp tables. I observed some clusters which had as many as 300 temp tables. The large number of tables can result in performance problems. A table has about 1 MB of JVM heap space overhead. For Cassandra pods particularly with smaller heap sizes, this could contribute to excessive GC which would result in high CPU usage and requests timing out. Version-Release number of selected component (if applicable): How reproducible: We would end up with orphaned (in the sense that they won't ever get deleted) temp tables any time the compression job fails to complete successfully. Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info:
The number temp file is growing after running metrics for one day, not between 12-14, it is 22 now Attached metrics logs, but the logs are short, can see the full logs # oc -n openshift-infra exec hawkular-cassandra-1-b8cww -- ls -alR /cassandra_data/ | grep -i temp drwxr-sr-x. 4 1000040000 1000040000 38 May 28 09:00 data_temp_2018052806-80073da0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 11:00 data_temp_2018052808-7fd99df0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 13:00 data_temp_2018052810-80352b70623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 15:00 data_temp_2018052812-c946eb50623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 17:00 data_temp_2018052814-c8bd9710623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 19:00 data_temp_2018052816-c83469e0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 21:00 data_temp_2018052818-c8eb84e0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 23:00 data_temp_2018052820-c9a2c6f0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 29 01:00 data_temp_2018052822-c974d920623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 258 May 29 01:00 data_temp_2018052900-c9192490623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 06:30 data_temp_2018052902-c88fd050623f11e8a7c0db96bf8c5620 drwxr-sr-x. 4 1000040000 1000040000 38 May 28 06:30 data_temp_2018052904-c86230a0623f11e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 08:24 data_temp_2018052906-8bbac8e0625011e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 10:24 data_temp_2018052908-4f443520626111e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 12:24 data_temp_2018052910-12ce1690627211e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 14:24 data_temp_2018052912-d65538e0628211e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 16:24 data_temp_2018052914-99de2ff0629311e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 18:24 data_temp_2018052916-5d6663b062a411e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 20:24 data_temp_2018052918-20efa8e062b511e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 28 22:24 data_temp_2018052920-e47a74b062c511e8a7c0db96bf8c5620 drwxr-sr-x. 3 1000040000 1000040000 21 May 29 00:24 data_temp_2018052922-a800fac062d611e8a7c0db96bf8c5620 # oc -n openshift-infra exec hawkular-cassandra-1-b8cww -- du -sh /cassandra_data/data/hawkular_metrics 7.5M /cassandra_data/data/hawkular_metrics # oc -n openshift-infra exec hawkular-cassandra-1-b8cww -- cqlsh --ssl -e "select * from hawkular_metrics.scheduled_jobs_idx" time_slice | job_id | job_name | job_params | job_type | status | trigger --------------------------+--------------------------------------+----------------------+------------+----------------------+--------+-------------------------------------------------------------------------------------------------------------------- 2018-05-29 02:24:00+0000 | 9debdbfc-773b-43b1-b271-743311a1d083 | TEMP_TABLE_CREATOR | {} | TEMP_TABLE_CREATOR | null | {type: 1, trigger_time: 1527560640000, delay: 60000, interval: 7200000, repeat_count: null, execution_count: null} 2018-05-29 03:00:00+0000 | 4f69448b-b3a4-49e7-a77b-5261cd108fba | TEMP_DATA_COMPRESSOR | {} | TEMP_DATA_COMPRESSOR | null | {type: 1, trigger_time: 1527562800000, delay: 60000, interval: 7200000, repeat_count: null, execution_count: null} (2 rows) # oc -n openshift-infra exec hawkular-cassandra-1-b8cww -- cqlsh --ssl -e "select * from hawkular_metrics.finished_jobs_idx" time_slice | job_id ------------+-------- (0 rows) metrics version is v3.7.51-1
Created attachment 1445007 [details] metrics pods log
Junqi, When Cassandra drop a table the corresponding directory on disk does not get deleted. By default Cassandra creates a snapshot of the table before dropping it. We have set the auto_snapshot property in cassandra.yaml (in cassandra pod) to false so snapshots should not be generated by default. You will need to run the following query to determine the number of tables: $ oc -n openshift-infra exec <cassandra pod> -- cqlsh --ssl -e "select table_name from system_schema.tables where keyspace_name = 'hawkular_metrics'" My apologies for not pointing this out sooner.
There are not two many data_temp tables after metrics running for one day, metrics version is v3.7.51-1 # oc -n openshift-infra exec hawkular-cassandra-1-8znt6 -- cqlsh --ssl -e "select table_name from system_schema.tables where keyspace_name = 'hawkular_metrics'" table_name ---------------------- active_time_slices cassalog data data_0 data_compressed data_temp_2018053000 data_temp_2018053002 data_temp_2018053004 data_temp_2018053006 data_temp_2018053008 data_temp_2018053010 data_temp_2018053012 data_temp_2018053014 data_temp_2018053016 data_temp_2018053018 data_temp_2018053020 finished_jobs_idx jobs leases locks metrics_idx metrics_tags_idx retentions_idx scheduled_jobs_idx sys_config tasks tenants tenants_by_time (28 rows)
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-2018:1798