1 files changed, 119 insertions, 0 deletions
diff --git a/jstests/noPassthrough/conn_pool_csrs.js b/jstests/noPassthrough/conn_pool_csrs.js
new file mode 100644
index 00000000000..2f6f7aa32de
--- /dev/null
+++ b/jstests/noPassthrough/conn_pool_csrs.js
@@ -0,0 +1,119 @@
+load("jstests/libs/parallelTester.js");
+
+/**
+ * @tags: [requires_replication, requires_sharding]
+ *
+ * Test that servers can be configured with distinct size limits for
+ * connection pools that are connected to a config server.
+ *
+ * Heavily modified from jstest/noPassthrough/set_step_params.js
+ */
+
+(function() {
+"use strict";
+
+const poolSizeLogId = 6265600;
+
+const rsMin = 10;
+const rsMax = 20;
+
+const baselineParameters = {
+    ShardingTaskExecutorPoolMinSize: rsMin,
+    ShardingTaskExecutorPoolMaxSize: rsMax,
+    ShardingTaskExecutorPoolMinSizeForConfigServers: 4,
+    ShardingTaskExecutorPoolMaxSizeForConfigServers: 6,
+};
+
+const mongosParameters = Object.assign(
+    {logComponentVerbosity: tojson({network: {connectionPool: 5}})}, baselineParameters);
+
+const st = new ShardingTest({
+    config: {nodes: 1},
+    shards: 1,
+    rs0: {nodes: 1},
+    mongos: [{setParameter: mongosParameters}],
+});
+const mongos = st.s0;
+const configServer = st.c0;
+const mongod = st.rs0.getPrimary();
+
+const adminCmd = req => assert.commandWorked(mongos.adminCommand(req));
+
+const populateTestDb = () => {
+    const db = mongos.getDB('test');
+    const coll = db.test;
+    assert.commandWorked(coll.insert({x: 1}));
+    assert.commandWorked(coll.insert({x: 2}));
+    assert.commandWorked(coll.insert({x: 3}));
+};
+
+const setCSPoolBounds = (min, max) => {
+    adminCmd(Object.assign({"setParameter": 1}, {
+        ShardingTaskExecutorPoolMinSizeForConfigServers: min,
+        ShardingTaskExecutorPoolMaxSizeForConfigServers: max,
+    }));
+};
+
+// Make mongos open a connection to the config server. This is done by issuing a
+// query that mongos will connect to the config server to execute.
+const connectConfigServer = () => {
+    jsTestLog('Cause Config Server connection');
+    assert.commandWorked(mongos.getDB('config').runCommand(
+        {find: "databases", limit: 1, "$readPreference": {mode: 'primary'}}));
+};
+
+// The (only) mongod has a 'test' database.
+const connectMongodServer = () => {
+    jsTestLog('Cause Mongod Server connection');
+    assert.commandWorked(mongos.getDB('test').runCommand(
+        {find: "test", limit: 1, "$readPreference": {mode: 'primary'}}));
+};
+
+// Waits until mongos emits a log line indicating that the conn pool
+// `targetHost` is being resized. Returns all such lines.
+const awaitUpdateHost = targetHost => {
+    let hits;
+    assert.soon(() => {
+        let log = checkLog.getGlobalLog(st.s);
+        // jsTestLog(`Fetched log: """${log}"""`);
+        hits = checkLog.getGlobalLog(mongos)
+                   .map(line => JSON.parse(line))
+                   .filter(o => o.id == poolSizeLogId)
+                   .filter(o => o.attr.host == targetHost);
+        return hits.length > 0;
+    }, `log lines id:${poolSizeLogId} for target ${targetHost}`, 10 * 1000, 1 * 1000, {
+        runHangAnalyzer: false
+    });
+    return hits;
+};
+
+populateTestDb();
+
+// Try a few {min,max} pairs.
+for (const [min, max] of [[4, 6], [10, 20], [2, 4], [-1, -1]]) {
+    jsTestLog(`Try ConfigServer pool bounds [${min},${max}]`);
+    setCSPoolBounds(min, max);
+
+    adminCmd({dropConnections: 1, hostAndPort: [configServer.host]});
+    adminCmd({clearLog: 'global'});
+    connectConfigServer();
+    for (let o of awaitUpdateHost(configServer.host)) {
+        const cascade = (x, fallback) => x >= 0 ? x : fallback;
+        assert.eq(o.attr.minConns, cascade(min, rsMin));
+        assert.eq(o.attr.maxConns, cascade(max, rsMax));
+    }
+
+    // Make sure the setting doesn't affect non-ConfigServer pools.
+    adminCmd({dropConnections: 1, hostAndPort: [mongod.host]});
+    adminCmd({clearLog: 'global'});
+    connectMongodServer();
+    for (let o of awaitUpdateHost(mongod.host)) {
+        assert.eq(o.attr.minConns, rsMin);
+        assert.eq(o.attr.maxConns, rsMax);
+    }
+
+    adminCmd(Object.assign({"setParameter": 1}, baselineParameters));
+}
+
+st.stop();
+})();