diff --git a/src/functions/definitions.ts b/src/functions/definitions.ts
index 6593ec4..460e4ca 100644
--- a/src/functions/definitions.ts
+++ b/src/functions/definitions.ts
@@ -38,12 +38,14 @@ export type AccumulatorOptions<T, R, S> = S extends FlushStrategy.sampling
 
 export interface RollingFlushOptions<T, R> {
     windowLength: number;
-    afterFlush?: (flushed: Array<T>) => Array<R>;
+    flushMapper?: (flushed: Array<T>) => Array<R>;
+    timeout?: number;
 }
 
 export interface SlidingFlushOptions<T, R> {
     windowLength: number;
-    afterFlush?: (flushed: Array<T>) => Array<R>;
+    flushMapper?: (flushed: Array<T>) => Array<R>;
+    timeout?: number;
 }
 
 export interface SlidingFlushResult<T> {
@@ -53,6 +55,7 @@ export interface SlidingFlushResult<T> {
 export interface SamplingFlushOptions<T, R> {
     condition: (event: T, buffer: Array<T>) => boolean;
     flushMapper?: (flushed: Array<T>) => Array<R>;
+    timeout?: number;
 }
 
 export interface SamplingFlushResult<T> {
diff --git a/src/functions/functions.spec.ts b/src/functions/functions.spec.ts
index decd771..5289065 100644
--- a/src/functions/functions.spec.ts
+++ b/src/functions/functions.spec.ts
@@ -1404,20 +1404,21 @@ test.cb("parallel() parallel mapping", t => {
     source.push(null);
 });
 
-test.cb.only("accumulator() buffering strategy", t => {
+test.cb("accumulator() buffering strategy clears buffer on condition", t => {
+    t.plan(2);
     let chunkIndex = 0;
     interface TestObject {
         ts: number;
         key: string;
     }
     const source = new Readable({ objectMode: true });
-    const expectedElements = [
+    const firstFlush = [
         { ts: 0, key: "a" },
         { ts: 1, key: "b" },
         { ts: 2, key: "c" },
         { ts: 2, key: "d" },
-        { ts: 3, key: "e" },
     ];
+    const secondFlush = [{ ts: 3, key: "e" }];
 
     source
         .pipe(
@@ -1428,15 +1429,98 @@ test.cb.only("accumulator() buffering strategy", t => {
         .on("data", (flush: TestObject[]) => {
             if (chunkIndex === 0) {
                 chunkIndex++;
-                t.deepEqual(flush, expectedElements.slice(0, 4));
+                t.deepEqual(flush, firstFlush);
             } else {
-                t.deepEqual(flush, expectedElements.slice(4));
+                t.deepEqual(flush, secondFlush);
             }
         })
         .on("error", e => t.end)
         .on("end", () => {
             t.end();
         });
-    expectedElements.forEach(element => source.push(element));
+    source.push([...firstFlush, ...secondFlush]);
     source.push(null);
 });
+
+test.cb("accumulator() buffering strategy clears buffer on timeout", t => {
+    t.plan(2);
+    let chunkIndex = 0;
+    interface TestObject {
+        ts: number;
+        key: string;
+    }
+    const source = new Readable({ objectMode: true, read: () => {} });
+    const firstFlush = [{ ts: 0, key: "a" }, { ts: 1, key: "b" }];
+    const secondFlush = [
+        { ts: 2, key: "c" },
+        { ts: 2, key: "d" },
+        { ts: 3, key: "e" },
+    ];
+    source
+        .pipe(
+            accumulator(FlushStrategy.sampling, {
+                condition: (event: TestObject) => event.ts > 3,
+                timeout: 1000,
+            }),
+        )
+        .on("data", (flush: TestObject[]) => {
+            if (chunkIndex === 0) {
+                chunkIndex++;
+                t.deepEqual(flush, firstFlush);
+            } else {
+                t.deepEqual(flush, secondFlush);
+            }
+        })
+        .on("error", e => t.end)
+        .on("end", () => {
+            t.end();
+        });
+    source.push(firstFlush);
+    setTimeout(() => {
+        source.push(secondFlush);
+        source.push(null);
+    }, 2000);
+});
+
+test.cb(
+    "accumulator() buffering strategy clears buffer on condition or timeout",
+    t => {
+        t.plan(3);
+        let chunkIndex = 0;
+        interface TestObject {
+            ts: number;
+            key: string;
+        }
+        const source = new Readable({ objectMode: true, read: () => {} });
+        const firstFlush = [{ ts: 0, key: "a" }, { ts: 1, key: "b" }];
+        const secondFlush = [{ ts: 2, key: "c" }, { ts: 2, key: "d" }];
+        const thirdFlush = [{ ts: 3, key: "e" }];
+        source
+            .pipe(
+                accumulator(FlushStrategy.sampling, {
+                    condition: (event: TestObject) => event.ts > 2,
+                    timeout: 1000,
+                }),
+            )
+            .on("data", (flush: TestObject[]) => {
+                if (chunkIndex === 0) {
+                    chunkIndex++;
+                    t.deepEqual(flush, firstFlush);
+                } else if (chunkIndex === 1) {
+                    chunkIndex++;
+                    t.deepEqual(flush, secondFlush);
+                } else {
+                    t.deepEqual(flush, thirdFlush);
+                }
+            })
+            .on("error", e => t.end)
+            .on("end", () => {
+                t.end();
+            });
+        source.push(firstFlush);
+        setTimeout(() => {
+            source.push([...secondFlush, ...thirdFlush]);
+            source.push(null);
+        }, 2000);
+    },
+);
diff --git a/src/functions/functions.ts b/src/functions/functions.ts
index 40a534c..b9fd812 100644
--- a/src/functions/functions.ts
+++ b/src/functions/functions.ts
@@ -525,7 +525,6 @@ export function batch(batchSize: number = 1000, maxBatchAge: number = 500) {
             callback();
         },
         flush(callback) {
-            console.error("flushing");
             sendChunk(this);
             callback();
         },
@@ -642,10 +641,18 @@ export function accumulator<T, R, S extends FlushStrategy>(
     options: AccumulatorOptions<T, R, S>,
 ) {
     const buffer: Array<T> = [];
-    return new Transform({
+    let handle: NodeJS.Timer | null = null;
+    if (options.timeout) {
+        handle = setInterval(() => {
+            if (buffer.length > 0) {
+                transform.push(buffer);
+                buffer.length = 0;
+            }
+        }, options.timeout);
+    }
+    const transform = new Transform({
         objectMode: true,
         async transform(data: T[] | T, encoding, callback) {
-            callback();
             switch (flushStrategy) {
                 case FlushStrategy.sampling: {
                     if (!Array.isArray(data)) data = [data];
@@ -655,6 +662,7 @@ export function accumulator<T, R, S extends FlushStrategy>(
                         buffer,
                         this,
                     );
+                    callback();
                     break;
                 }
                 case FlushStrategy.sliding: {
@@ -663,8 +671,10 @@ export function accumulator<T, R, S extends FlushStrategy>(
             }
         },
         flush(callback) {
+            handle && clearInterval(handle);
             this.push(buffer);
             callback();
         },
     });
+    return transform;
 }
diff --git a/src/functions/index.ts b/src/functions/index.ts
index 6f2c058..a6ae32e 100644
--- a/src/functions/index.ts
+++ b/src/functions/index.ts
@@ -245,7 +245,6 @@ export function parallelMap<T, R>(
     parallel?: number,
     sleepTime?: number,
 ) {
-    console.log("hi");
     return baseFunctions.parallelMap(mapper, parallel, sleepTime);
 }