send.buffer.bytes — Kafka Consumer Configuration
The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used.
Description
The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used.
Default Values by Kafka Version
| Kafka Version | Default Value |
|---|---|
| 0.9.0 | 131072 |
| 0.10.0 | 131072 |
| 0.10.1 | 131072 |
| 0.10.2 | 131072 |
| 0.11.0 | 131072 |
| 1.0 | 131072 |
| 1.1 | 131072 |
| 2.0 | 131072 |
| 2.1 | 131072 |
| 2.2 | 131072 |
| 2.3 | 131072 |
| 2.4 | 131072 |
| 2.5 | 131072 |
| 2.6 | 131072 (128 kibibytes) |
| 2.7 | 131072 (128 kibibytes) |
| 2.8 | 131072 (128 kibibytes) |
| 3.0 | 131072 (128 kibibytes) |
| 3.1 | 131072 (128 kibibytes) |
| 3.2 | 131072 (128 kibibytes) |
| 3.3 | 131072 (128 kibibytes) |
| 3.4 | 131072 (128 kibibytes) |
| 3.5 | 131072 (128 kibibytes) |
| 3.6 | 131072 (128 kibibytes) |
| 3.7 | 131072 (128 kibibytes) |
| 3.8 | 131072 (128 kibibytes) |
| 3.9 | 131072 (128 kibibytes) |
| 4.0 | 131072 (128 kibibytes) |
| 4.1 | 131072 (128 kibibytes) |
| 4.2 | 131072 (128 kibibytes) |
Tuning Recommendation
| Profile | Recommended | Why |
|---|---|---|
| producer / throughput | 1048576 | Increasing the TCP send buffer to 1MB allows the OS to buffer more in-flight bytes without producer blocking, especially critical on high-latency links (>5ms RTT) where the bandwidth-delay product exceeds 128KB. |
| producer / latency | 131072 | The 128KB OS send buffer is already well-tuned for low-latency workloads with small batches; the kernel will not buffer more than one batch before flushing, keeping TCP write latency minimal without increasing kernel memory per connection. |
Related Configs
receive.buffer.bytes · batch.size · connections.max.idle.ms
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