Attempt to handle a stream being silently killed in the background

brianc · brianc · commit 8a7b43aa7e50 · 2020-02-26T11:47:40.000-06:00
diff --git a/packages/pg-pool/index.js b/packages/pg-pool/index.js
@@ -116,11 +116,20 @@ class Pool extends EventEmitter {
     const pendingItem = this._pendingQueue.shift()
     if (this._idle.length) {
       const idleItem = this._idle.pop()
-      clearTimeout(idleItem.timeoutId)
       const client = idleItem.client
-      const idleListener = idleItem.idleListener
+      clearTimeout(idleItem.timeoutId)
 
-      return this._acquireClient(client, pendingItem, idleListener, false)
+      // TODO(bmc): we need a better state represetation on the client itself
+      // to indicate if it's connecting, idle, running a query, closed, etc...
+      // but for now we can look at it's stream.
+      // remove this client, it's died in the background - this can happen
+      // in aws lambdas - they go idle and the streams are closed without an error
+      if (client.connection.stream.readyState !== 'open') {
+        this._remove(client)
+      } else {
+        const idleListener = idleItem.idleListener
+        return this._acquireClient(client, pendingItem, idleListener, false)
+      }
     }
     if (!this._isFull()) {
       return this.newClient(pendingItem)
diff --git a/packages/pg-pool/test/background-socket-terminiation.js b/packages/pg-pool/test/background-socket-terminiation.js
@@ -0,0 +1,31 @@
+'use strict'
+const net = require('net')
+const co = require('co')
+const expect = require('expect.js')
+
+const describe = require('mocha').describe
+const it = require('mocha').it
+
+const Pool = require('../')
+
+describe('a socket disconnecting in the background', () => {
+  it('should leave the pool in a usable state', async () => {
+    const pool = new Pool({ max: 1 })
+    // just run any arbitrary query
+    const client = await pool.connect()
+    await client.query('SELECT NOW()')
+    // return the client
+    client.release()
+
+    // now kill the socket in the background
+    client.connection.stream.end()
+
+    // now try to query again, it should work
+    await pool.query('SELECT NOW()')
+    await pool.query('SELECT NOW()')
+    await pool.query('SELECT NOW()')
+    await pool.query('SELECT NOW()')
+
+    await pool.end()
+  })
+})
