util: hide duplicated stack frames when using util.inspect

lib/internal/util/inspect.js

@@ -1305,13 +1305,47 @@ function identicalSequenceRange(a, b) {
           len++;
         }
         if (len > 3) {
-          return { len, offset: i };
+          return [len, i];
         }
       }
     }
   }
 
-  return { len: 0, offset: 0 };
+  return [0, 0];
+}
+
+function getDuplicateErrorFrameRanges(frames) {
+  const result = [];
+  for (let i = 0; i < frames.length - 3; i++) {
+    // Find the first duplicate frame.
+    const pos = frames.indexOf(frames[i], i + 1);
+    const range = pos - i;
+    if (pos !== -1 && range >= 3) {
+      let duplicateRanges = 0;
+      // Compare ranges line-by-line
+      for (let nextStart = i + range; nextStart < frames.length - range; nextStart += range) {
+        let allEqual = true;
+        for (let j = 0; j < range; j++) {
+          if (frames[i + j] !== frames[nextStart + j]) {
+            allEqual = false;
+            break;
+          }
+        }
+        if (allEqual) {
+          // Matched. We have a duplicate range
+          duplicateRanges++;
+        } else {
+          break;
+        }
+      }
+      if (duplicateRanges !== 0) {
+        result.push([i + range, range, duplicateRanges]);
+      }
+      i += range * duplicateRanges;
+    }
+  }
+
+  return result;
 }
 
 function getStackString(ctx, error) {
@@ -1345,14 +1379,30 @@ function getStackFrames(ctx, err, stack) {
     const causeStackStart = StringPrototypeIndexOf(causeStack, '\n    at');
     if (causeStackStart !== -1) {
       const causeFrames = StringPrototypeSplit(StringPrototypeSlice(causeStack, causeStackStart + 1), '\n');
-      const { len, offset } = identicalSequenceRange(frames, causeFrames);
+      const { 0: len, 1: offset } = identicalSequenceRange(frames, causeFrames);
       if (len > 0) {
         const skipped = len - 2;
         const msg = `    ... ${skipped} lines matching cause stack trace ...`;
         frames.splice(offset + 1, skipped, ctx.stylize(msg, 'undefined'));
       }
     }
   }
+
+  // Remove recursive repetitive stack frames in long stacks
+  if (frames.length > 10) {
+    const ranges = getDuplicateErrorFrameRanges(frames);
+
+    while (ranges.length) {
+      const { 0: offset, 1: len, 2: duplicateRanges } = ranges.pop();
+      const msg = `    ... removed ${len * duplicateRanges} duplicate lines ` +
+        'matching former ' +
+        (duplicateRanges > 1 ?
+          `${len} lines ${duplicateRanges} times...` :
+          'lines ...');
+      frames.splice(offset, len * duplicateRanges, ctx.stylize(msg, 'undefined'));
+    }
+  }
+
   return frames;
 }
 

test/parallel/test-util-inspect.js

@@ -2920,6 +2920,72 @@ assert.strictEqual(
   process.cwd = originalCWD;
 }
 
+{
+  // Use a fake stack to verify the expected colored outcome.
+  const err = new Error('Hide duplicate frames in long stack');
+  err.stack = [
+    'Error: CWD is grayed out, even cwd that are percent encoded!',
+    '    at A.<anonymous> (/foo/node_modules/bar/baz.js:2:7)',
+    '    at Module._compile (node:internal/modules/cjs/loader:827:30)',
+    '    at Fancy (node:vm:697:32)',
+    '    at tryModuleLoad (node:internal/modules/cjs/foo:629:12)',
+    '    at Function.Module._load (node:internal/modules/cjs/loader:621:3)',
+    '    at Fancy (node:vm:697:32)',
+    '    at tryModuleLoad (node:internal/modules/cjs/foo:629:12)',
+    '    at Function.Module._load (node:internal/modules/cjs/loader:621:3)',
+    '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)',
+    '    at require (node:internal/modules/helpers:14:16)',
+    '    at Array.forEach (<anonymous>)',
+    '    at require (node:internal/modules/helpers:14:16)',
+    '    at Array.forEach (<anonymous>)',
+    `    at foobar/test/parallel/test-util-inspect.js:2760:12`,
+    `    at Object.<anonymous> (foobar/node_modules/m/folder/file.js:2753:10)`,
+    '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)',
+    '    at require (node:internal/modules/helpers:14:16)',
+    '    at Array.forEach (<anonymous>)',
+    `    at foobar/test/parallel/test-util-inspect.js:2760:12`,
+    `    at Object.<anonymous> (foobar/node_modules/m/folder/file.js:2753:10)`,
+    '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)',
+    '    at require (node:internal/modules/helpers:14:16)',
+    '    at Array.forEach (<anonymous>)',
+    `    at foobar/test/parallel/test-util-inspect.js:2760:12`,
+    `    at Object.<anonymous> (foobar/node_modules/m/folder/file.js:2753:10)`,
+    '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)',
+    '    at require (node:internal/modules/helpers:14:16)',
+    '    at Array.forEach (<anonymous>)',
+    `    at foobar/test/parallel/test-util-inspect.js:2760:12`,
+    `    at Object.<anonymous> (foobar/node_modules/m/folder/file.js:2753:10)`,
+    '    at /test/test-util-inspect.js:2239:9',
+    '    at getActual (node:assert:592:5)',
+  ].join('\n');
+
+  assert.strictEqual(
+    util.inspect(err, { colors: true }),
+    'Error: CWD is grayed out, even cwd that are percent encoded!\n' +
+      '    at A.<anonymous> (/foo/node_modules/\x1B[4mbar\x1B[24m/baz.js:2:7)\n' +
+      '\x1B[90m    at Module._compile (node:internal/modules/cjs/loader:827:30)\x1B[39m\n' +
+      '\x1B[90m    at Fancy (node:vm:697:32)\x1B[39m\n' +
+      '    at tryModuleLoad (node:internal/modules/cjs/foo:629:12)\n' +
+      '\x1B[90m    at Function.Module._load (node:internal/modules/cjs/loader:621:3)\x1B[39m\n' +
+      '\x1B[90m    ... removed 3 duplicate lines matching former lines ...\x1B[39m\n' +
+      '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)\n' +
+      '\x1B[90m    at require (node:internal/modules/helpers:14:16)\x1B[39m\n' +
+      '    at Array.forEach (<anonymous>)\n' +
+      '\x1B[90m    at require (node:internal/modules/helpers:14:16)\x1B[39m\n' +
+      '    at Array.forEach (<anonymous>)\n' +
+      '    at foobar/test/parallel/test-util-inspect.js:2760:12\n' +
+      '    at Object.<anonymous> (foobar/node_modules/\x1B[4mm\x1B[24m/folder/file.js:2753:10)\n' +
+      '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)\n' +
+      '\x1B[90m    ... removed 10 duplicate lines matching former 5 lines 2 times...\x1B[39m\n' +
+      '\x1B[90m    at require (node:internal/modules/helpers:14:16)\x1B[39m\n' +
+      '    at Array.forEach (<anonymous>)\n' +
+      '    at foobar/test/parallel/test-util-inspect.js:2760:12\n' +
+      '    at Object.<anonymous> (foobar/node_modules/\x1B[4mm\x1B[24m/folder/file.js:2753:10)\n' +
+      '    at /test/test-util-inspect.js:2239:9\n' +
+      '\x1B[90m    at getActual (node:assert:592:5)\x1B[39m'
+  );
+}
+
 {
   // Cross platform checks.
   const err = new Error('foo');