From 4128f43f533019642d1ab0b0c8d80d84b3632ba1 Mon Sep 17 00:00:00 2001
From: Kanwar Ujjaval Singh <4216199+kanwarujjaval@users.noreply.github.com>
Date: Wed, 7 Aug 2024 18:01:19 +0530
Subject: [PATCH] experimental asynchooks to track stuck promises

---
 plugins/system-utility/api/AsyncTracker.js | 118 +++++++++++++++++++++
 plugins/system-utility/api/api.js          |   6 ++
 2 files changed, 124 insertions(+)
 create mode 100644 plugins/system-utility/api/AsyncTracker.js

diff --git a/plugins/system-utility/api/AsyncTracker.js b/plugins/system-utility/api/AsyncTracker.js
new file mode 100644
index 00000000000..460c9f2efb1
--- /dev/null
+++ b/plugins/system-utility/api/AsyncTracker.js
@@ -0,0 +1,118 @@
+const asyncHooks = require('async_hooks');
+const common = require('../../../api/utils/common.js');
+const log = common.log('AsyncTracker');
+const path = require('path');
+/**
+ * Class to track asynchronous operations and log potentially stuck operations.
+ */
+class AsyncTracker {
+    /**
+     * Creates an instance of AsyncTracker.
+     * @param {number} [timeoutMs=5000] - The timeout in milliseconds to consider an async operation as stuck.
+     */
+    constructor(timeoutMs = 10000) {
+        this.timeoutMs = timeoutMs;
+        this.asyncOps = new Map();
+        this.hook = asyncHooks.createHook({
+            init: this.init.bind(this),
+            destroy: this.destroy.bind(this)
+        });
+        // this.logFile = fs.createWriteStream('async-ops.log', { flags: 'a' });
+    }
+
+    /**
+     * Initializes tracking for a new async operation.
+     * @param {number} asyncId - The unique identifier for the async operation.
+     * @param {string} type - The type of the async operation.
+     * @param {number} triggerAsyncId - The unique identifier of the async operation that triggered this one.
+     */
+    init(asyncId, type, triggerAsyncId) {
+        if (type === 'PROMISE') {
+            const startTime = Date.now();
+            const stackTrace = this.captureStackTrace();
+            this.asyncOps.set(asyncId, { type, startTime, triggerAsyncId, stackTrace });
+        }
+    }
+
+    /**
+     * Removes tracking for a completed async operation.
+     * @param {number} asyncId - The unique identifier for the async operation.
+     */
+    destroy(asyncId) {
+        this.asyncOps.delete(asyncId);
+    }
+
+    /**
+     * Captures the current stack trace.
+     * @returns {string} The captured stack trace.
+     */
+    captureStackTrace() {
+        const stackTraceLimit = Error.stackTraceLimit;
+        Error.stackTraceLimit = Infinity;
+        const obj = {};
+        Error.captureStackTrace(obj, this.captureStackTrace);
+        Error.stackTraceLimit = stackTraceLimit;
+        return obj.stack;
+    }
+
+    /**
+     * Starts tracking async operations.
+     */
+    start() {
+        this.hook.enable();
+    }
+
+    /**
+     * Stops tracking async operations.
+     */
+    stop() {
+        this.hook.disable();
+    }
+
+    /**
+     * Logs potentially stuck async operations.
+     */
+    logStuckOperations() {
+        const now = Date.now();
+        log.d('Checking for stuck async operations...');
+
+        for (const [asyncId, { type, startTime, triggerAsyncId, stackTrace }] of this.asyncOps) {
+            const elapsedTime = now - startTime;
+            if (elapsedTime > this.timeoutMs) {
+                log.d(`Potentially stuck ${type} operation detected:`);
+                log.d(`AsyncID: ${asyncId}`);
+                log.d(`TriggerAsyncID: ${triggerAsyncId}`);
+                log.d(`Elapsed time: ${elapsedTime}ms`);
+                this.logStackTrace(stackTrace);
+                log.d('---');
+            }
+        }
+
+        if (this.asyncOps.size === 0) {
+            log.d('No pending async operations detected.');
+        }
+    }
+
+    /**
+     * Logs a stack trace.
+     * @param {string} stackTrace - The stack trace to log.
+     */
+    logStackTrace(stackTrace) {
+        const stackLines = stackTrace.split('\n');
+        for (let i = 1; i < stackLines.length; i++) {
+            const line = stackLines[i].trim();
+            if (line.startsWith('at ')) {
+                const match = line.match(/at (?:(.+?)\s+\()?(?:(.+?):(\d+):(\d+))/);
+                if (match) {
+                    const [, fnName, filename, lineNumber, columnNumber] = match;
+                    log.d(`  at ${fnName || '<anonymous>'} (${path.basename(filename)}:${lineNumber}:${columnNumber})`);
+                }
+                else {
+                    log.d(`  ${line}`);
+                }
+            }
+        }
+    }
+}
+
+module.exports = AsyncTracker;
\ No newline at end of file
diff --git a/plugins/system-utility/api/api.js b/plugins/system-utility/api/api.js
index f5e956ea63c..ae996dcb4e0 100644
--- a/plugins/system-utility/api/api.js
+++ b/plugins/system-utility/api/api.js
@@ -6,6 +6,12 @@ var plugin = {},
     log = common.log('system-utility:api'),
     cluster = require("cluster");
 
+const AsyncTracker = require('./AsyncTracker');
+const asyncTracker = new AsyncTracker();
+asyncTracker.start();
+setInterval(() => asyncTracker.logStuckOperations(), 30000);
+
+
 const processName = (cluster.isMaster ? "master" : "worker") + "-" + process.pid;
 const profilerCmds = ["startProfiler", "stopProfiler", "startInspector", "stopInspector"];
 let numberOfWorkers;