Editing Thundering herd problem (section)

== Mitigation ==
The Linux kernel serializes responses for requests to a single file descriptor, so only one thread or process is woken up.<ref>{{cite web |url=https://stackoverflow.com/a/23002010/56280|title=Does the Thundering Herd Problem exist on Linux anymore|website=stackoverflow.com|access-date=2019-07-09}}</ref> For epoll() in version 4.5 of the Linux kernel, the EPOLLEXCLUSIVE flag was added. Thus several epoll sets (different threads or different processes) may wait on the same resource and only one set will be woken up.  For certain workloads this flag can give significant processing time reduction.<ref>{{Cite web|last=Madars|first=Vitolins|date=2015-12-05|title=EPOLLEXCLUSIVE Linux Kernel patch testing|url=https://mvitolin.wordpress.com/2015/12/05/endurox-testing-epollexclusive-flag/|archive-url=|archive-date=|access-date=2020-08-11|website=mvitolin|language=en}}</ref>

Similarly in Microsoft Windows, [[Input/output completion port|I/O completion ports]] can mitigate the thundering herd problem, as they can be configured such that only one of the threads waiting on the completion port is woken up when an event occurs.<ref>{{Cite web|url=https://xania.org/200807/iocp|title=IO Completion Ports — Matt Godbolt's blog |website=xania.org|access-date=2019-01-23}}</ref>

In systems that rely on a backoff mechanism (e.g. [[exponential backoff]]), the clients will retry failed calls by waiting a specific amount of time between consecutive retries. In order to avoid the thundering herd problem, [[jitter]] can be purposefully introduced in order to break the synchronization across the clients, thereby avoiding collisions. In this approach, randomness is added to the wait intervals between retries, so that clients are no longer synchronized.