commit 4ed03f206457414bfcd3592afec4a0b3f71d821d
author Primiano Tucci <primiano@google.com> Mon Mar 15 14:26:07 2021 +0000
committer Primiano Tucci <primiano@google.com> Mon Mar 15 14:26:07 2021 +0000
tree 57e6511b86eb6586b27db381bef8975c750144a5
parent c061d214c9da2dd3f9ced1ccfa2e9244c09f017f

UI: Build wasm with -g2 to preserve symbols, fix OOM message

The previous emscripten+wasm toolchain roll broke C++ symbols
in Wasm crashes and, recursively, the special casing around
known crashes (e.g. OOM).
This CL:
- Adds -g2 to preserve function names, now explicitly required
  when building with -O3.
- Adds ASSERTIONS=1 (1 in debug builds) to get the error message
  ("cannot enlarge memory") from OOMs.
- Tweaks the OOM detection code, as the message slightly changed
  (it doesn't mention "array" anymore).
- Makes the OOM message a bit more actionable.

Bug: 182711686
Bug: 181218057
Bug: 181237261
Change-Id: I84909f08bd2d93b4545cd5f0a5e29f94dd126bee

gn/standalone/wasm.gni

diff --git a/gn/standalone/wasm.gni b/gn/standalone/wasm.gni
index a66b34b..bcf952b 100644
--- a/gn/standalone/wasm.gni
+++ b/gn/standalone/wasm.gni
@@ -72,9 +72,23 @@
       "-lworkerfs.js",  # For FS.filesystems.WORKERFS
     ]
     if (is_debug) {
-      _target_ldflags += [ "-g4" ]
+      _target_ldflags += [
+        "-s",
+        "ASSERTIONS=2",
+        "-s",
+        "SAFE_HEAP=1",
+        "-s",
+        "STACK_OVERFLOW_CHECK=1",
+        "-g4",
+        "-O0",
+      ]
     } else {
-      _target_ldflags += [ "-O3" ]
+      _target_ldflags += [
+        "-s",
+        "ASSERTIONS=1",
+        "-g2",  # Required for getting C++ symbol names.
+        "-O3",
+      ]
     }
 
     if (defined(invoker.js_library)) {

ui/src/frontend/error_dialog.ts

diff --git a/ui/src/frontend/error_dialog.ts b/ui/src/frontend/error_dialog.ts
index 87195b8..9fba9a0 100644
--- a/ui/src/frontend/error_dialog.ts
+++ b/ui/src/frontend/error_dialog.ts
@@ -34,7 +34,7 @@
   const now = performance.now();
 
   // Here we rely on the exception message from onCannotGrowMemory function
-  if (errLog.includes('Cannot enlarge memory arrays')) {
+  if (errLog.includes('Cannot enlarge memory')) {
     showOutOfMemoryDialog();
     // Refresh timeLastReport to prevent a different error showing a dialog
     timeLastReport = now;
@@ -185,19 +185,26 @@
 function showOutOfMemoryDialog() {
   const url =
       'https://perfetto.dev/docs/quickstart/trace-analysis#get-trace-processor';
-  const description = 'This is a limitation of your browser. ' +
-      'You can get around this by loading the trace ' +
-      'directly in the trace_processor binary.';
 
+  const tpCmd = 'curl -LO https://get.perfetto.dev/trace_processor\n' +
+      'chmod +x ./trace_processor\n' +
+      'trace_processor --httpd /path/to/trace.pftrace\n' +
+      '# Reload the UI, it will prompt to use the HTTP+RPC interface';
   showModal({
     title: 'Oops! Your WASM trace processor ran out of memory',
     content: m(
         'div',
-        m('span', description),
+        m('span',
+          'The in-memory representation of the trace is too big ' +
+              'for the browser memory limits (typically 2GB per tab).'),
+        m('br'),
+        m('span',
+          'You can work around this problem by using the trace_processor ' +
+              'native binary as an accelerator for the UI as follows:'),
         m('br'),
         m('br'),
-        m('span', 'Example command:'),
-        m('.modal-bash', '> trace_processor trace.pftrace --http'),
+        m('.modal-bash', tpCmd),
+        m('br'),
         m('span', 'For details see '),
         m('a', {href: url, target: '_blank'}, url),
         ),

ui/src/frontend/index.ts

diff --git a/ui/src/frontend/index.ts b/ui/src/frontend/index.ts
index fef5661..553b830 100644
--- a/ui/src/frontend/index.ts
+++ b/ui/src/frontend/index.ts
@@ -285,7 +285,7 @@
     'object-src': ['none'],
     'connect-src': [
       `'self'`,
-      'http://127.0.0.1:9001',  // For trace_processor_shell --http.
+      'http://127.0.0.1:9001',  // For trace_processor_shell --httpd.
       'https://www.google-analytics.com',
       'https://*.googleapis.com',  // For Google Cloud Storage fetches.
       'blob:',