Introduce Bun.unsafe.gcAggressionLevel API

packages/bun-types/bun.d.ts

@@ -1699,6 +1699,23 @@ declare module "bun" {
 
     /** Mock bun's segfault handler. You probably don't want to use this */
     segfault(): void;
+
+    /**
+     * Force the garbage collector to run extremely often,
+     * especially inside `bun:test`.
+     *
+     * - `0`: default, disable
+     * - `1`: asynchronously call the garbage collector more often
+     * - `2`: synchronously call the garbage collector more often.
+     *
+     * This is a global setting. It's useful for debugging seemingly random crashes.
+     *
+     * `BUN_GARBAGE_COLLECTOR_LEVEL` environment variable is also supported.
+     *
+     * @param level
+     * @returns The previous level
+     */
+    gcAggressionLevel(level: 0 | 1 | 2): 0 | 1 | 2;
   }
   export const unsafe: unsafe;
 

src/bun.js/api/bun.zig

@@ -1990,10 +1990,30 @@ pub const Unsafe = struct {
             .arrayBufferToString = .{
                 .rfn = arrayBufferToString,
             },
+            .gcAggressionLevel = .{
+                .rfn = JSC.wrapWithHasContainer(Unsafe, "gcAggressionLevel", false, false, false),
+            },
         },
         .{},
     );
 
+    pub fn gcAggressionLevel(
+        globalThis: *JSC.JSGlobalObject,
+        value_: ?JSValue,
+    ) JSValue {
+        const ret = JSValue.jsNumber(@as(i32, @enumToInt(globalThis.bunVM().aggressive_garbage_collection)));
+
+        if (value_) |value| {
+            switch (value.coerce(i32, globalThis)) {
+                1 => globalThis.bunVM().aggressive_garbage_collection = .mild,
+                2 => globalThis.bunVM().aggressive_garbage_collection = .aggressive,
+                0 => globalThis.bunVM().aggressive_garbage_collection = .none,
+                else => {},
+            }
+        }
+        return ret;
+    }
+
     // For testing the segfault handler
     pub fn __debug__doSegfault(
         _: void,

test/bun.js/gc.js

@@ -12,3 +12,13 @@ export function gcTick(trace = false) {
     setTimeout(resolve, 0);
   });
 }
+
+export function withoutAggressiveGC(block) {
+  const origGC = Bun.unsafe.gcAggressionLevel();
+  Bun.unsafe.gcAggressionLevel(0);
+  try {
+    return block();
+  } finally {
+    Bun.unsafe.gcAggressionLevel(origGC);
+  }
+}