Make ExternalCarbonConnectionImpl fiber stack size a gflag (default 64 KiB)

Summary: Human Darrien - For the mcrouter folks, let us know if this is a reasonable change to make. We are getting fiber overflows in our tests as of late since D100058297 in our tests.

We’re hoping to provide an override in the least invasive way so we can have these tests run again. Let us know if this is reasonable 🙂‍↕️

The fbjava/privacy/zone:zone_library_test integration tests fail in mode/dev with folly::fibers Fiber stack overflow detected. Root cause: mcrouter/lib/carbon/connection/ExternalCarbonConnectionImpl.cpp‘s ThreadInfo constructs its FiberManager with the default Options (16 KiB stack), which becomes 32 KiB in dev after the stackSizeMultiplier=2 is applied. The AsyncMcClient::create path running on that fiber overflows the 32 KiB stack in unoptimized builds where frames are larger.

Added a cacheclient_external_fiber_stack_size gflag defaulting to 65536 bytes (64 KiB), and wired it into the FiberManager::Options.stackSize used by ThreadInfo. The new default gives 64 KiB × 2 = 128 KiB in dev (and 64 KiB in opt), enough headroom for AsyncMcClient::create while still being reasonable for a per-fiber allocation. Operators can tune this further at runtime if needed.

Differential Revision: D101644600

fbshipit-source-id: b75d788c6339a76265de634da7e23af83cb70d30

Mcrouter

Mcrouter (pronounced mc router) is a memcached protocol router for scaling memcached deployments. It’s a core component of cache infrastructure at Facebook and Instagram where mcrouter handles almost 5 billion requests per second at peak.

Mcrouter is developed and maintained by Facebook.

See https://github.com/facebook/mcrouter/wiki to get started.

Quick start guide

New! Ubuntu package available

Currently, we support Ubuntu Bionic (18.04) amd64. Here is how to install it:

Add the repo key:

$ wget -O - https://facebook.github.io/mcrouter/debrepo/bionic/PUBLIC.KEY | sudo apt-key add

Add the following line to apt sources file /etc/apt/sources.list

deb https://facebook.github.io/mcrouter/debrepo/bionic bionic contrib

Update the local repo cache:

$ sudo apt-get update

Install mcrouter:

$ sudo apt-get install mcrouter

Installing From Source

See https://github.com/facebook/mcrouter/wiki/mcrouter-installation for more detailed installation instructions.

Mcrouter depends on folly, wangle, fizz, and fbthrift.

The installation is a standard autotools flow:

$ autoreconf --install
$ ./configure
$ make
$ sudo make install
$ mcrouter --help

Assuming you have a memcached instance on the local host running on port 5001, the simplest mcrouter setup is:

$ mcrouter \
    --config-str='{"pools":{"A":{"servers":["127.0.0.1:5001"]}},
                  "route":"PoolRoute|A"}' \
    -p 5000
$ echo -ne "get key\r\n" | nc 0 5000

(nc is the GNU Netcat, http://netcat.sourceforge.net/)

Features

Memcached ASCII protocol
Connection pooling
Multiple hashing schemes
Prefix routing
Replicated pools
Production traffic shadowing
Online reconfiguration
Flexible routing
Destination health monitoring/automatic failover
Cold cache warm up
Broadcast operations
Reliable delete stream
Multi-cluster support
Rich stats and debug commands
Quality of service
Large values
Multi-level caches
IPv6 support
SSL support

Links

Documentation: https://github.com/facebook/mcrouter/wiki Engineering discussions and support: https://www.facebook.com/groups/mcrouter

License

Licensed under the MIT license: https://github.com/facebook/mcrouter/blob/master/LICENSE