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/*
* Test that the balancer is redistributing data based on the actual amount of data
* for a collection on each node, converging when the size difference becomes small.
*/
(function() {
'use strict';
load("jstests/sharding/libs/find_chunks_util.js");
load("jstests/libs/fail_point_util.js");
const maxChunkSizeMB = 1;
const st = new ShardingTest({
shards: 2,
mongos: 1,
other: {
chunkSize: maxChunkSizeMB,
enableBalancer: false,
configOptions: {setParameter: {logComponentVerbosity: tojson({sharding: {verbosity: 2}})}}
}
});
const dbName = 'test';
const coll = st.getDB(dbName).getCollection('foo');
const ns = coll.getFullName();
const mongos = st.s;
const shard0 = st.shard0.shardName;
const shard1 = st.shard1.shardName;
// Shard collection with one chunk on shard0 [MinKey, 0) and one chunk on shard1 [0, MinKey)
assert.commandWorked(mongos.adminCommand({enablesharding: dbName, primaryShard: shard0}));
assert.commandWorked(mongos.adminCommand({shardcollection: ns, key: {_id: 1}}));
assert.commandWorked(mongos.adminCommand({split: ns, middle: {_id: 0}}));
assert.commandWorked(mongos.adminCommand({moveChunk: ns, find: {_id: 0}, to: shard1}));
const bigString = 'X'.repeat(1024 * 1024); // 1MB
// Insert 10MB of documents in range [MinKey, 0) on shard0
var bulk = coll.initializeUnorderedBulkOp();
for (var i = -1; i > -11; i--) {
bulk.insert({_id: i, s: bigString});
}
assert.commandWorked(bulk.execute());
// Insert 3MB of documents in range [0, MaxKey) on shard1
bulk = coll.initializeUnorderedBulkOp();
for (var i = 0; i < 3; i++) {
bulk.insert({_id: i, s: bigString});
}
assert.commandWorked(bulk.execute());
// Create 3 more chunks on shard0
assert.commandWorked(mongos.adminCommand({split: ns, middle: {_id: 1}}));
assert.commandWorked(mongos.adminCommand({split: ns, middle: {_id: 2}}));
assert.commandWorked(mongos.adminCommand({split: ns, middle: {_id: 3}}));
// At this point, the distribution of chunks for the testing collection is the following:
// - On shard0 (10MB):
// { "_id" : { "$minKey" : 1 } } -->> { "_id" : 0 }
// - On shard1 (3MB):
// { "_id" : 0 } -->> { "_id" : 1 }
// { "_id" : 1 } -->> { "_id" : 2 }
// { "_id" : 2 } -->> { "_id" : 3 }
// { "_id" : 3 } -->> { "_id" : { "$maxKey" : 1 } }
jsTestLog("Printing sharding status before starting balancer");
st.printShardingStatus();
st.startBalancer();
st.awaitCollectionBalance(coll, 60000 /* timeout */, 1000 /* interval */);
const chunksBeforeNoopRound = findChunksUtil.findChunksByNs(st.config, ns).toArray();
// Check that the collection is balanced
st.verifyCollectionIsBalanced(coll);
jsTestLog("Printing sharding status after waiting for collection balance");
st.printShardingStatus();
// Wait for some more rounds and then check the balancer is not wrongly moving around data
configureFailPointForRS(
st.configRS.nodes, 'overrideBalanceRoundInterval', {intervalMs: 100}, 'alwaysOn');
st.awaitBalancerRound();
st.awaitBalancerRound();
st.awaitBalancerRound();
st.stopBalancer();
jsTestLog("Printing sharding status after stopping balancer");
st.printShardingStatus();
// Check that no move has been performed during the noop rounds (if the routing table did not
// change, it means data are still balanced)
const chunksAfterNoopRound = findChunksUtil.findChunksByNs(st.config, ns).toArray();
assert.eq(chunksBeforeNoopRound, chunksAfterNoopRound);
st.stop();
})();
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