config: drop ProduceRequestTimeout to 10s, doc more

30s is too generous. Even 10s is likely too generous, since usually
writes at p99 finish within 100ms.

pkg/kgo/config.go

@@ -280,7 +280,7 @@ func (cfg *cfg) validate() error {
  // Some random producer settings.
  {name: "max buffered records", v: int64(cfg.maxBufferedRecords), allowed: 1, badcmp: i64lt},
  {name: "linger", v: int64(cfg.linger), allowed: int64(time.Minute), badcmp: i64gt, durs: true},
- {name: "produce timeout", v: int64(cfg.produceTimeout), allowed: int64(time.Second), badcmp: i64lt, durs: true},
+ {name: "produce timeout", v: int64(cfg.produceTimeout), allowed: int64(100 * time.Millisecond), badcmp: i64lt, durs: true},
  {name: "record timeout", v: int64(cfg.recordTimeout), allowed: int64(time.Second), badcmp: func(l, r int64) (bool, string) {
  if l == 0 {
  return false, "" // we print nothing when things are good
@@ -446,7 +446,7 @@ func defaultCfg() cfg {
  compression: []CompressionCodec{SnappyCompression(), NoCompression()},
  maxRecordBatchBytes: 1000000, // Kafka max.message.bytes default is 1000012
  maxBufferedRecords: 10000,
- produceTimeout: 30 * time.Second,
+ produceTimeout: 10 * time.Second,
  recordRetries: math.MaxInt64, // effectively unbounded
  partitioner: StickyKeyPartitioner(nil), // default to how Kafka partitions
 
@@ -874,11 +874,13 @@ func RecordPartitioner(partitioner Partitioner) ProducerOpt {
 }
 
 // ProduceRequestTimeout sets how long Kafka broker's are allowed to respond to
-// produce requests, overriding the default 30s. If a broker exceeds this
+// produce requests, overriding the default 10s. If a broker exceeds this
 // duration, it will reply with a request timeout error.
 //
-// This corresponds to Kafka's request.timeout.ms setting, but only applies to
-// produce requests.
+// This somewhat corresponds to Kafka's request.timeout.ms setting, but only
+// applies to produce requests. This settings sets the TimeoutMillis field in
+// the produce request itself. The ConnTimeoutOverhead is applied as a write
+// limit and read limit in addition to this.
 func ProduceRequestTimeout(limit time.Duration) ProducerOpt {
  return producerOpt{func(cfg *cfg) { cfg.produceTimeout = limit }}
 }