fix: prevent memory leaks from AbortController closures (#12024)

5 files changed, 184 insertions, 15 deletions

diff --git a/packages/opencode/src/tool/codesearch.ts b/packages/opencode/src/tool/codesearch.ts
index 369cdb450..28dd4eb49 100644
--- a/packages/opencode/src/tool/codesearch.ts
+++ b/packages/opencode/src/tool/codesearch.ts
@@ -1,6 +1,7 @@
 import z from "zod"
 import { Tool } from "./tool"
 import DESCRIPTION from "./codesearch.txt"
+import { abortAfterAny } from "../util/abort"
 
 const API_CONFIG = {
   BASE_URL: "https://mcp.exa.ai",
@@ -73,8 +74,7 @@ export const CodeSearchTool = Tool.define("codesearch", {
       },
     }
 
-    const controller = new AbortController()
-    const timeoutId = setTimeout(() => controller.abort(), 30000)
+    const { signal, clearTimeout } = abortAfterAny(30000, ctx.abort)
 
     try {
       const headers: Record<string, string> = {
@@ -86,10 +86,10 @@ export const CodeSearchTool = Tool.define("codesearch", {
         method: "POST",
         headers,
         body: JSON.stringify(codeRequest),
-        signal: AbortSignal.any([controller.signal, ctx.abort]),
+        signal,
       })
 
-      clearTimeout(timeoutId)
+      clearTimeout()
 
       if (!response.ok) {
         const errorText = await response.text()
@@ -120,7 +120,7 @@ export const CodeSearchTool = Tool.define("codesearch", {
         metadata: {},
       }
     } catch (error) {
-      clearTimeout(timeoutId)
+      clearTimeout()
 
       if (error instanceof Error && error.name === "AbortError") {
         throw new Error("Code search request timed out")
diff --git a/packages/opencode/src/tool/webfetch.ts b/packages/opencode/src/tool/webfetch.ts
index a4a54598c..c9479b9df 100644
--- a/packages/opencode/src/tool/webfetch.ts
+++ b/packages/opencode/src/tool/webfetch.ts
@@ -2,6 +2,7 @@ import z from "zod"
 import { Tool } from "./tool"
 import TurndownService from "turndown"
 import DESCRIPTION from "./webfetch.txt"
+import { abortAfterAny } from "../util/abort"
 
 const MAX_RESPONSE_SIZE = 5 * 1024 * 1024 // 5MB
 const DEFAULT_TIMEOUT = 30 * 1000 // 30 seconds
@@ -36,8 +37,7 @@ export const WebFetchTool = Tool.define("webfetch", {
 
     const timeout = Math.min((params.timeout ?? DEFAULT_TIMEOUT / 1000) * 1000, MAX_TIMEOUT)
 
-    const controller = new AbortController()
-    const timeoutId = setTimeout(() => controller.abort(), timeout)
+    const { signal, clearTimeout } = abortAfterAny(timeout, ctx.abort)
 
     // Build Accept header based on requested format with q parameters for fallbacks
     let acceptHeader = "*/*"
@@ -55,8 +55,6 @@ export const WebFetchTool = Tool.define("webfetch", {
         acceptHeader =
           "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8"
     }
-
-    const signal = AbortSignal.any([controller.signal, ctx.abort])
     const headers = {
       "User-Agent":
         "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36",
@@ -72,7 +70,7 @@ export const WebFetchTool = Tool.define("webfetch", {
         ? await fetch(params.url, { signal, headers: { ...headers, "User-Agent": "opencode" } })
         : initial
 
-    clearTimeout(timeoutId)
+    clearTimeout()
 
     if (!response.ok) {
       throw new Error(`Request failed with status code: ${response.status}`)
diff --git a/packages/opencode/src/tool/websearch.ts b/packages/opencode/src/tool/websearch.ts
index 9cc6af72d..beedd9c7c 100644
--- a/packages/opencode/src/tool/websearch.ts
+++ b/packages/opencode/src/tool/websearch.ts
@@ -1,6 +1,7 @@
 import z from "zod"
 import { Tool } from "./tool"
 import DESCRIPTION from "./websearch.txt"
+import { abortAfterAny } from "../util/abort"
 
 const API_CONFIG = {
   BASE_URL: "https://mcp.exa.ai",
@@ -91,8 +92,7 @@ export const WebSearchTool = Tool.define("websearch", async () => {
         },
       }
 
-      const controller = new AbortController()
-      const timeoutId = setTimeout(() => controller.abort(), 25000)
+      const { signal, clearTimeout } = abortAfterAny(25000, ctx.abort)
 
       try {
         const headers: Record<string, string> = {
@@ -104,10 +104,10 @@ export const WebSearchTool = Tool.define("websearch", async () => {
           method: "POST",
           headers,
           body: JSON.stringify(searchRequest),
-          signal: AbortSignal.any([controller.signal, ctx.abort]),
+          signal,
         })
 
-        clearTimeout(timeoutId)
+        clearTimeout()
 
         if (!response.ok) {
           const errorText = await response.text()
@@ -137,7 +137,7 @@ export const WebSearchTool = Tool.define("websearch", async () => {
           metadata: {},
         }
       } catch (error) {
-        clearTimeout(timeoutId)
+        clearTimeout()
 
         if (error instanceof Error && error.name === "AbortError") {
           throw new Error("Search request timed out")
diff --git a/packages/opencode/src/util/abort.ts b/packages/opencode/src/util/abort.ts
new file mode 100644
index 000000000..3e7cfd8b2
--- /dev/null
+++ b/packages/opencode/src/util/abort.ts
@@ -0,0 +1,35 @@
+/**
+ * Creates an AbortController that automatically aborts after a timeout.
+ *
+ * Uses bind() instead of arrow functions to avoid capturing the surrounding
+ * scope in closures. Arrow functions like `() => controller.abort()` capture
+ * request bodies and other large objects, preventing GC for the timer lifetime.
+ *
+ * @param ms Timeout in milliseconds
+ * @returns Object with controller, signal, and clearTimeout function
+ */
+export function abortAfter(ms: number) {
+  const controller = new AbortController()
+  const id = setTimeout(controller.abort.bind(controller), ms)
+  return {
+    controller,
+    signal: controller.signal,
+    clearTimeout: () => globalThis.clearTimeout(id),
+  }
+}
+
+/**
+ * Combines multiple AbortSignals with a timeout.
+ *
+ * @param ms Timeout in milliseconds
+ * @param signals Additional signals to combine
+ * @returns Combined signal that aborts on timeout or when any input signal aborts
+ */
+export function abortAfterAny(ms: number, ...signals: AbortSignal[]) {
+  const timeout = abortAfter(ms)
+  const signal = AbortSignal.any([timeout.signal, ...signals])
+  return {
+    signal,
+    clearTimeout: timeout.clearTimeout,
+  }
+}
diff --git a/packages/opencode/test/memory/abort-leak.test.ts b/packages/opencode/test/memory/abort-leak.test.ts
new file mode 100644
index 000000000..b202c9127
--- /dev/null
+++ b/packages/opencode/test/memory/abort-leak.test.ts
@@ -0,0 +1,136 @@
+import { describe, test, expect } from "bun:test"
+import path from "path"
+import { Instance } from "../../src/project/instance"
+import { WebFetchTool } from "../../src/tool/webfetch"
+
+const projectRoot = path.join(__dirname, "../..")
+
+const ctx = {
+  sessionID: "test",
+  messageID: "",
+  callID: "",
+  agent: "build",
+  abort: new AbortController().signal,
+  messages: [],
+  metadata: () => {},
+  ask: async () => {},
+}
+
+const MB = 1024 * 1024
+const ITERATIONS = 50
+
+const getHeapMB = () => {
+  Bun.gc(true)
+  return process.memoryUsage().heapUsed / MB
+}
+
+describe("memory: abort controller leak", () => {
+  test("webfetch does not leak memory over many invocations", async () => {
+    await Instance.provide({
+      directory: projectRoot,
+      fn: async () => {
+        const tool = await WebFetchTool.init()
+
+        // Warm up
+        await tool.execute({ url: "https://example.com", format: "text" }, ctx).catch(() => {})
+
+        Bun.gc(true)
+        const baseline = getHeapMB()
+
+        // Run many fetches
+        for (let i = 0; i < ITERATIONS; i++) {
+          await tool.execute({ url: "https://example.com", format: "text" }, ctx).catch(() => {})
+        }
+
+        Bun.gc(true)
+        const after = getHeapMB()
+        const growth = after - baseline
+
+        console.log(`Baseline: ${baseline.toFixed(2)} MB`)
+        console.log(`After ${ITERATIONS} fetches: ${after.toFixed(2)} MB`)
+        console.log(`Growth: ${growth.toFixed(2)} MB`)
+
+        // Memory growth should be minimal - less than 1MB per 10 requests
+        // With the old closure pattern, this would grow ~0.5MB per request
+        expect(growth).toBeLessThan(ITERATIONS / 10)
+      },
+    })
+  }, 60000)
+
+  test("compare closure vs bind pattern directly", async () => {
+    const ITERATIONS = 500
+
+    // Test OLD pattern: arrow function closure
+    // Store closures in a map keyed by content to force retention
+    const closureMap = new Map<string, () => void>()
+    const timers: Timer[] = []
+    const controllers: AbortController[] = []
+
+    Bun.gc(true)
+    Bun.sleepSync(100)
+    const baseline = getHeapMB()
+
+    for (let i = 0; i < ITERATIONS; i++) {
+      // Simulate large response body like webfetch would have
+      const content = `${i}:${"x".repeat(50 * 1024)}` // 50KB unique per iteration
+      const controller = new AbortController()
+      controllers.push(controller)
+
+      // OLD pattern - closure captures `content`
+      const handler = () => {
+        // Actually use content so it can't be optimized away
+        if (content.length > 1000000000) controller.abort()
+      }
+      closureMap.set(content, handler)
+      const timeoutId = setTimeout(handler, 30000)
+      timers.push(timeoutId)
+    }
+
+    Bun.gc(true)
+    Bun.sleepSync(100)
+    const after = getHeapMB()
+    const oldGrowth = after - baseline
+
+    console.log(`OLD pattern (closure): ${oldGrowth.toFixed(2)} MB growth (${closureMap.size} closures)`)
+
+    // Cleanup after measuring
+    timers.forEach(clearTimeout)
+    controllers.forEach((c) => c.abort())
+    closureMap.clear()
+
+    // Test NEW pattern: bind
+    Bun.gc(true)
+    Bun.sleepSync(100)
+    const baseline2 = getHeapMB()
+    const handlers2: (() => void)[] = []
+    const timers2: Timer[] = []
+    const controllers2: AbortController[] = []
+
+    for (let i = 0; i < ITERATIONS; i++) {
+      const _content = `${i}:${"x".repeat(50 * 1024)}` // 50KB - won't be captured
+      const controller = new AbortController()
+      controllers2.push(controller)
+
+      // NEW pattern - bind doesn't capture surrounding scope
+      const handler = controller.abort.bind(controller)
+      handlers2.push(handler)
+      const timeoutId = setTimeout(handler, 30000)
+      timers2.push(timeoutId)
+    }
+
+    Bun.gc(true)
+    Bun.sleepSync(100)
+    const after2 = getHeapMB()
+    const newGrowth = after2 - baseline2
+
+    // Cleanup after measuring
+    timers2.forEach(clearTimeout)
+    controllers2.forEach((c) => c.abort())
+    handlers2.length = 0
+
+    console.log(`NEW pattern (bind): ${newGrowth.toFixed(2)} MB growth`)
+    console.log(`Improvement: ${(oldGrowth - newGrowth).toFixed(2)} MB saved`)
+
+    expect(newGrowth).toBeLessThanOrEqual(oldGrowth)
+  })
+})