Details
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Bug
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Resolution: Cannot Reproduce
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Major - P3
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None
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3.0.0
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None
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Fully Compatible
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ALL
Description
We noticed that one of our 4 shards had a secondary with high replication lag.
Replica shard log has periodic very slow serverStatus with large values for "after oplog":
2015-03-18T18:30:44.539+0000 I COMMAND [conn82] serverStatus was very slow:
{ after basic: 0, after asserts: 0, after connections: 0, after cursors: 0, after extra_info: 0, after globalLock: 0, after locks: 0, after network: 0, after opcounters: 0, after opcountersRepl: 0, after oplog: 72189, after repl: 72189, after storageEngine: 72189, after wiredTiger: 72189, at end: 72189 }Restarted the replica shard hoping that this was a fluke, but the shard quickly went back to a low insertion rate.
Running db.getSiblingDB("local").oplog.rs.stats() produces:
{
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"ns" : "local.oplog.rs",
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"count" : 174896077,
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"size" : 125833992359,
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"avgObjSize" : 719,
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"storageSize" : 62140203008,
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"capped" : true,
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"max" : -1,
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"maxSize" : NumberLong("125829120000"),
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"wiredTiger" : {
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"metadata" : {
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"formatVersion" : 1,
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"oplogKeyExtractionVersion" : 1
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},
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"creationString" : "allocation_size=4KB,app_metadata=(formatVersion=1,oplogKeyExtractionVersion=1),block_allocation=best,block_compressor=snappy,cache_resident=0,checkpoint=(WiredTigerCheckpoint.23998=(addr=\"01e30ad2de81e436162abee3ddf13ebde46538e310e3ddf17bb3e43c3b848d808080e50e77d81fc0e50bad737fc0\",order=23998,time=1426703669,size=50154676224,write_gen=20018662)),checkpoint_lsn=(7514,101134976),checksum=uncompressed,collator=,columns=,dictionary=0,format=btree,huffman_key=,huffman_value=,id=9,internal_item_max=0,internal_key_max=0,internal_key_truncate=,internal_page_max=4KB,key_format=q,key_gap=10,leaf_item_max=0,leaf_key_max=0,leaf_page_max=32KB,leaf_value_max=1MB,memory_page_max=10m,os_cache_dirty_max=0,os_cache_max=0,prefix_compression=0,prefix_compression_min=4,split_deepen_min_child=0,split_deepen_per_child=0,split_pct=90,value_format=u,version=(major=1,minor=1)",
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"type" : "file",
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"uri" : "statistics:table:local/collection-2--4790446482890547801",
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"LSM" : {
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"bloom filters in the LSM tree" : 0,
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"bloom filter false positives" : 0,
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"bloom filter hits" : 0,
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"bloom filter misses" : 0,
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"bloom filter pages evicted from cache" : 0,
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"bloom filter pages read into cache" : 0,
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"total size of bloom filters" : 0,
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"sleep for LSM checkpoint throttle" : 0,
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"chunks in the LSM tree" : 0,
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"highest merge generation in the LSM tree" : 0,
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"queries that could have benefited from a Bloom filter that did not exist" : 0,
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"sleep for LSM merge throttle" : 0
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},
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"block-manager" : {
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"file allocation unit size" : 4096,
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"blocks allocated" : 176633,
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"checkpoint size" : 50154676224,
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"allocations requiring file extension" : 0,
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"blocks freed" : 206417,
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"file magic number" : 120897,
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"file major version number" : 1,
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"minor version number" : 0,
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"file bytes available for reuse" : 12083351552,
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"file size in bytes" : 62140203008
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},
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"btree" : {
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"column-store variable-size deleted values" : 0,
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"column-store fixed-size leaf pages" : 0,
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"column-store internal pages" : 0,
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"column-store variable-size leaf pages" : 0,
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"pages rewritten by compaction" : 0,
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"number of key/value pairs" : 0,
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"fixed-record size" : 0,
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"maximum tree depth" : 32,
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"maximum internal page key size" : 368,
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"maximum internal page size" : 4096,
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"maximum leaf page key size" : 3276,
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"maximum leaf page size" : 32768,
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"maximum leaf page value size" : 1048576,
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"overflow pages" : 0,
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"row-store internal pages" : 0,
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"row-store leaf pages" : 0
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},
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"cache" : {
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"bytes read into cache" : 5684148385,
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"bytes written from cache" : 5626150236,
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"checkpoint blocked page eviction" : 11413,
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"unmodified pages evicted" : 175446,
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"page split during eviction deepened the tree" : 1,
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"modified pages evicted" : 3911,
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"data source pages selected for eviction unable to be evicted" : 2675,
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"hazard pointer blocked page eviction" : 589,
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"internal pages evicted" : 1882,
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"pages split during eviction" : 585,
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"in-memory page splits" : 553,
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"overflow values cached in memory" : 0,
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"pages read into cache" : 178344,
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"overflow pages read into cache" : 0,
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"pages written from cache" : 176607
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},
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"compression" : {
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"raw compression call failed, no additional data available" : 0,
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"raw compression call failed, additional data available" : 0,
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"raw compression call succeeded" : 0,
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"compressed pages read" : 176000,
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"compressed pages written" : 173316,
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"page written failed to compress" : 3,
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"page written was too small to compress" : 3288
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},
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"cursor" : {
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"create calls" : 128,
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"insert calls" : 10935859,
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"bulk-loaded cursor-insert calls" : 0,
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"cursor-insert key and value bytes inserted" : 5679356593,
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"next calls" : 7327404,
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"prev calls" : 35,
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"remove calls" : 561,
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"cursor-remove key bytes removed" : 5049,
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"reset calls" : 10937358,
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"search calls" : 0,
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"search near calls" : 1122,
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"update calls" : 0,
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"cursor-update value bytes updated" : 0
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},
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"reconciliation" : {
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"dictionary matches" : 0,
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"internal page multi-block writes" : 25,
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"leaf page multi-block writes" : 605,
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"maximum blocks required for a page" : 236,
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"internal-page overflow keys" : 0,
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"leaf-page overflow keys" : 0,
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"overflow values written" : 0,
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"pages deleted" : 2780,
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"page checksum matches" : 5294,
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"page reconciliation calls" : 6475,
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"page reconciliation calls for eviction" : 1885,
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"leaf page key bytes discarded using prefix compression" : 0,
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"internal page key bytes discarded using suffix compression" : 175625
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},
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"session" : {
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"object compaction" : 0,
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"open cursor count" : 128
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},
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"transaction" : {
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"update conflicts" : 0
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}
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},
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"nindexes" : 0,
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"totalIndexSize" : 0,
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"indexSizes" : {
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},
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"ok" : 1
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}
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