/
constants.go
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/
constants.go
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// Copyright 2016 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Radu Berinde (radu@cockroachlabs.com)
package base
import "time"
const (
// DefaultMaxClockOffset is the default maximum acceptable clock offset value.
// On Azure, clock offsets between 250ms and 500ms are common. On AWS and GCE,
// clock offsets generally stay below 250ms. See comments on Config.MaxOffset
// for more on this setting.
DefaultMaxClockOffset = 500 * time.Millisecond
// DefaultHeartbeatInterval is how often heartbeats are sent from the
// transaction coordinator to a live transaction. These keep it from
// being preempted by other transactions writing the same keys. If a
// transaction fails to be heartbeat within 2x the heartbeat interval,
// it may be aborted by conflicting txns.
DefaultHeartbeatInterval = 1 * time.Second
// DefaultSendNextTimeout is the duration to wait before trying another
// replica to send a KV batch.
//
// TODO(peter): The SendNextTimeout mechanism is intended to lower tail
// latencies by performing "speculative retries". In order to do so, the
// timeout needs to by very low, but it can't be too low or we add
// unnecessary network traffic and increase the likelihood of ambiguous
// results. The SendNextTimeout mechanism has been the source of several bugs
// and it is questionable about whether it is still necessary given that we
// shut down the connection on heartbeat timeouts.
//
// https://github.com/cockroachdb/cockroach/issues/15687
// https://github.com/cockroachdb/cockroach/issues/16119
//
// In advance of removing the SendNextTimeout mechanism completely, we're
// setting the value very high and will be paying attention to tail
// latencies.
DefaultSendNextTimeout = 10 * time.Minute
// SlowRequestThreshold is the amount of time to wait before considering a
// request to be "slow".
SlowRequestThreshold = 60 * time.Second
)