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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.
*
* @tags: [
* featureFlagBalanceAccordingToDataSize,
* requires_fcv_61,
* ]
*/
(function() {
'use strict';
load("jstests/sharding/libs/find_chunks_util.js");
function getCollSizeMB(ns, node) {
let res;
let collections = [{ns: ns}];
assert.soon(() => {
res = assert.commandWorkedOrFailedWithCode(
node.adminCommand({_shardsvrGetStatsForBalancing: 1, collections: collections}),
[ErrorCodes.NotYetInitialized]);
return res.ok;
});
return res['stats'][0]['collSize'];
}
const maxChunkSizeMB = 1;
const st = new ShardingTest(
{shards: 2, mongos: 1, other: {chunkSize: maxChunkSizeMB, enableBalancer: false}});
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();
assert.soon(function() {
return assert.commandWorked(st.s0.adminCommand({balancerCollectionStatus: ns}))
.balancerCompliant;
}, 'Timed out waiting for the collection to be balanced', 60000 /* timeout */, 1000 /* interval */);
// Check that the collection size diff between shards is small (2 * maxChunkSize)
const collSizeOnShard0BeforeNoopRounds = getCollSizeMB(ns, st.shard0.rs.getPrimary());
const collSizeOnShard1BeforeNoopRounds = getCollSizeMB(ns, st.shard1.rs.getPrimary());
const chunksBeforeNoopRound = findChunksUtil.findChunksByNs(st.config, ns).toArray();
var errMsg = '[BEFORE NOOP ROUND] Data on shard0 = ' + collSizeOnShard0BeforeNoopRounds +
' and data on shard 1 = ' + collSizeOnShard1BeforeNoopRounds +
' - chunks before noop round = ' + JSON.stringify(chunksBeforeNoopRound);
assert.lte(collSizeOnShard0BeforeNoopRounds - collSizeOnShard1BeforeNoopRounds,
3 * maxChunkSizeMB,
errMsg);
// Wait for some more rounds and then check the balancer is not wrongly moving around data
st.forEachConfigServer((conn) => {
conn.adminCommand({
configureFailPoint: 'overrideBalanceRoundInterval',
mode: 'alwaysOn',
data: {intervalMs: 100}
});
});
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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