fix(browser): Ensure suppressTracing does not leak when async

packages/cloudflare/src/async.ts

@@ -64,7 +64,16 @@ export function setAsyncLocalStorageAsyncContextStrategy(): void {
     });
   }
 
+  // In contrast to the browser, we can rely on async context isolation here
+  function suppressTracing<T>(callback: () => T): T {
+    return withScope(scope => {
+      scope.setSDKProcessingMetadata({ __SENTRY_SUPPRESS_TRACING__: true });
+      return callback();
+    });
+  }
+
   setAsyncContextStrategy({
+    suppressTracing,
     withScope,
     withSetScope,
     withIsolationScope,

packages/core/src/tracing/trace.ts

@@ -253,8 +253,15 @@ export function suppressTracing<T>(callback: () => T): T {
   }
 
   return withScope(scope => {
+    // Note: We do not wait for the callback to finish before we reset the metadata
+    // the reason for this is that otherwise, in the browser this can lead to very weird behavior
+    // as there is only a single top scope, if the callback takes longer to finish,
+    // other, unrelated spans may also be suppressed, which we do not want
+    // so instead, we only suppress tracing synchronoysly in the browser
     scope.setSDKProcessingMetadata({ [SUPPRESS_TRACING_KEY]: true });
-    return callback();
+    const res = callback();
+    scope.setSDKProcessingMetadata({ [SUPPRESS_TRACING_KEY]: undefined });
+    return res;
   });
 }
 

packages/core/test/lib/tracing/trace.test.ts

@@ -1975,6 +1975,40 @@ describe('suppressTracing', () => {
       expect(spanIsSampled(child)).toBe(false);
     });
   });
+
+  it('works with parallel processes', async () => {
+    const span = suppressTracing(() => {
+      return startInactiveSpan({ name: 'span' });
+    });
+
+    // Note: This is unintuitive, but it is the expected behavior
+    // because we only suppress tracing synchronously in the browser
+    const span2Promise = suppressTracing(async () => {
+      await new Promise(resolve => setTimeout(resolve, 100));
+      return startInactiveSpan({ name: 'span2' });
+    });
+
+    const span3Promise = suppressTracing(async () => {
+      const span = startInactiveSpan({ name: 'span3' });
+      await new Promise(resolve => setTimeout(resolve, 100));
+      return span;
+    });
+
+    const span4 = suppressTracing(() => {
+      return startInactiveSpan({ name: 'span' });
+    });
+
+    const span5 = startInactiveSpan({ name: 'span5' });
+
+    const span2 = await span2Promise;
+    const span3 = await span3Promise;
+
+    expect(spanIsSampled(span)).toBe(false);
+    expect(spanIsSampled(span2)).toBe(true);
+    expect(spanIsSampled(span3)).toBe(false);
+    expect(spanIsSampled(span4)).toBe(false);
+    expect(spanIsSampled(span5)).toBe(true);
+  });
 });
 
 describe('startNewTrace', () => {

packages/opentelemetry/test/trace.test.ts

@@ -1921,6 +1921,38 @@ describe('suppressTracing', () => {
       expect(spanIsSampled(child)).toBe(false);
     });
   });
+
+  it('works with parallel processes', async () => {
+    const span = suppressTracing(() => {
+      return startInactiveSpan({ name: 'span' });
+    });
+
+    const span2Promise = suppressTracing(async () => {
+      await new Promise(resolve => setTimeout(resolve, 100));
+      return startInactiveSpan({ name: 'span2' });
+    });
+
+    const span3Promise = suppressTracing(async () => {
+      const span = startInactiveSpan({ name: 'span3' });
+      await new Promise(resolve => setTimeout(resolve, 100));
+      return span;
+    });
+
+    const span4 = suppressTracing(() => {
+      return startInactiveSpan({ name: 'span' });
+    });
+
+    const span5 = startInactiveSpan({ name: 'span5' });
+
+    const span2 = await span2Promise;
+    const span3 = await span3Promise;
+
+    expect(spanIsSampled(span)).toBe(false);
+    expect(spanIsSampled(span2)).toBe(false);
+    expect(spanIsSampled(span3)).toBe(false);
+    expect(spanIsSampled(span4)).toBe(false);
+    expect(spanIsSampled(span5)).toBe(true);
+  });
 });
 
 function getSpanName(span: AbstractSpan): string | undefined {