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Type:
Task
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: None
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None
This came up in Jenkins with the following runs being "stuck" and running forever without terminating due to a stuck cache.
This reproduces readily on Linux for me.
############################################ # RUN PARAMETERS ############################################ abort=0 auto_throttle=1 backups=0 bitcnt=3 bloom=1 bloom_bit_count=45 bloom_hash_count=8 bloom_oldest=0 cache=55 checkpoints=1 checksum=uncompressed chunk_size=1 compaction=0 compression=snappy data_extend=0 data_source=table delete_pct=5 dictionary=0 direct_io=0 encryption=none evict_max=4 file_type=variable-length column-store firstfit=0 huffman_key=0 huffman_value=0 in_memory=0 insert_pct=31 internal_key_truncation=1 internal_page_max=14 isolation=snapshot key_gap=9 key_max=38 key_min=26 leaf_page_max=9 leak_memory=0 logging=0 logging_archive=0 logging_compression=none logging_prealloc=0 long_running_txn=0 lsm_worker_threads=4 merge_max=9 mmap=1 ops=100000 prefix_compression=1 prefix_compression_min=1 quiet=1 repeat_data_pct=47 reverse=0 rows=100000 runs=100 rebalance=1 salvage=1 split_pct=57 statistics=1 statistics_server=0 threads=18 timer=20 transaction-frequency=56 value_max=1206 value_min=6 verify=1 wiredtiger_config= write_pct=83 ############################################
In diving I found that the system here hit a horrible kind of loop within eviction,
where the evict server would constantly loop through and find pages to evict, however it would only ever evict clean pages and we would see cache->bytes_dirty_leaf still full after each lap. The value of cache->bytes_dirty_leaf would be above the dirty threshold with overhead.
Math:
| Variable | Value |
|---|---|
| cache->bytes_dirty_leaf | 10679988 |
| conn->cache_size + 1 | 57671681 |
| (cache->eviction_dirty_trigger * conn->cache_size)/100 | 11534336 |
| cache->overhead_pct | 8 |
| dirty_inuse | 11534387 (cache->bytes_dirty_leaf * 1.08) |
- duplicates
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WT-2913 stuck cache after latest merge
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- Closed
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