fetch investigation

src/bun.js/jsc/array_buffer.zig

@@ -250,30 +250,6 @@ pub const ArrayBuffer = extern struct {
             return this.value;
         }
 
-        // If it's not a mimalloc heap buffer, we're not going to call a deallocator
-        if (this.len > 0 and !bun.mimalloc.mi_is_in_heap_region(this.ptr)) {
-            log("toJS but will never free: {d} bytes", .{this.len});
-
-            if (this.typed_array_type == .ArrayBuffer) {
-                return makeArrayBufferWithBytesNoCopy(
-                    ctx,
-                    this.ptr,
-                    this.byte_len,
-                    null,
-                    null,
-                );
-            }
-
-            return makeTypedArrayWithBytesNoCopy(
-                ctx,
-                this.typed_array_type.toTypedArrayType(),
-                this.ptr,
-                this.byte_len,
-                null,
-                null,
-            );
-        }
-
         return this.toJSUnchecked(ctx);
     }
 

src/bun.js/webcore/fetch.zig

@@ -432,6 +432,8 @@ pub const FetchTasklet = struct {
                     readable.ptr.Bytes.onData(
                         .{
                             .owned_and_done = bun.ByteList.moveFromList(scheduled_response_buffer),
+                            // Investigate: owned_and_done is the correct behavior, is having bigger memory usage than temporary_and_done
+                            // .temporary_and_done = bun.ByteList.fromBorrowedSliceDangerous(chunk),
                         },
                         bun.default_allocator,
                     );

src/http/HTTPThread.zig

@@ -195,7 +195,7 @@ pub fn init(opts: *const InitOpts) void {
 pub fn onStart(opts: InitOpts) void {
     Output.Source.configureNamedThread("HTTP Client");
     bun.http.default_arena = Arena.init();
-    bun.http.default_allocator = bun.http.default_arena.allocator();
+    bun.http.default_allocator = bun.default_allocator;
 
     const loop = bun.jsc.MiniEventLoop.initGlobal(null, null);
 

test/js/web/fetch/fetch-leak.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test";
-import { bunEnv, bunExe, tls as COMMON_CERT, gc, isCI } from "harness";
+import { bunEnv, bunExe, bunRun, tls as COMMON_CERT, gc, isCI } from "harness";
 import { once } from "node:events";
 import { createServer } from "node:http";
 import { join } from "node:path";
@@ -184,3 +184,21 @@ test("do not leak", async () => {
     }
   }, 1e3);
 });
+
+test("should not leak using readable stream", async () => {
+  const buffer = Buffer.alloc(1024 * 128, "b");
+  using server = Bun.serve({
+    port: 0,
+    fetch: req => {
+      return new Response(buffer);
+    },
+  });
+
+  const { stdout, stderr } = bunRun(join(import.meta.dir, "fetch-leak-test-fixture-6.js"), {
+    ...bunEnv,
+    SERVER_URL: server.url.href,
+    MAX_MEMORY_INCREASE: "5", // in MB
+  });
+  expect(stderr).toBe("");
+  expect(stdout).toContain("done");
+});