apache/flink · error · IOException

Could not write {} bytes since the buffer is full.

Error message

Could not write {} bytes since the buffer is full.

What it means

Thrown by the DataOutputView-style write(DataInputView source, int numBytes) on Record's output view, used to bulk-copy bytes from a source view into the record's memory. Unlike other write methods it does NOT resize: it requires numBytes <= this.end - this.position (remaining space in the fixed-size target segment) and otherwise throws an IOException that the buffer is full.

Source

Thrown at flink-core/src/main/java/org/apache/flink/types/Record.java:1843

        @SuppressWarnings("restriction")
        private static final long BASE_OFFSET = UNSAFE.arrayBaseOffset(byte[].class);

        private static final boolean LITTLE_ENDIAN =
                (MemoryUtils.NATIVE_BYTE_ORDER == ByteOrder.LITTLE_ENDIAN);

        @Override
        public void skipBytesToWrite(int numBytes) throws IOException {
            int skippedBytes = skipBytes(numBytes);

            if (skippedBytes != numBytes) {
                throw new EOFException("Could not skip " + numBytes + " bytes.");
            }
        }

        @Override
        public void write(DataInputView source, int numBytes) throws IOException {
            if (numBytes > this.end - this.position) {
                throw new IOException(
                        "Could not write " + numBytes + " bytes since the buffer is full.");
            }

            source.readFully(this.memory, this.position, numBytes);
            this.position += numBytes;
        }
    }
}

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Ensure end - position >= numBytes before the call, or grow/reallocate the target segment first
2. Use write(byte[]) / writeUTF paths (which resize) instead of write(DataInputView, int) when the size is not guaranteed
3. Reset the target view's position/end appropriately when reusing buffers between records

Example fix

// before
target.write(source, numBytes); // numBytes > target remaining

// after
if (targetEnd - targetPos < numBytes) {
    growTarget(numBytes);
}
target.write(source, numBytes);

if (numBytes > end - position) {
    throw new IllegalStateException("target segment too small: need " + numBytes + ", have " + (end - position));
}
view.write(source, numBytes);

catch (IOException e) { if (e.getMessage().contains("buffer is full")) { growSegment(); view.write(source, numBytes); } else throw e; }

When it happens

Trigger: Calling write(source, numBytes) with numBytes greater than the space left between position and end in the target buffer; common when copying a large field into a nearly full segment or when end was set to a fixed capacity (not the array length).

Common situations: Splicing records between bounded memory segments; capacity computed from a stale position after a failed/partial copy; forgetting that this helper is capacity-bounded while write(byte[]) auto-resizes.

Related errors

• Byte array does not provide enough space to store requested
• Encoded string is too long: {}
• Could not skip {} bytes.
• Invalid version %d
• Serializing the source elements failed: {e.getMessage()}

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/d280a3d2a80a6c03. Report an issue: GitHub.