Add an expiring cache for the caching token authenticator

And maybe the webhook authorizer cache.

This cache has two primary advantages over the LRU cache used currently:

- Cache hits don't acquire an exclusive lock.
- More importantly, performance doesn't fallover when the access pattern
  scans a key space larger than an arbitrary size (e.g. the LRU
  capacity).

The downside of using an expiring cache here is that it doesn't have a
maximum size so it's suspectible to DoS when the input is user
controlled. This is not the case for successful authentications, and
successful authentications have a natural expiry so it might be a good
fit here.

It has some a few differences compared to:

3d7318f29d/staging/src/k8s.io/client-go/tools/cache/expiration_cache.go

- Expiration is not entirely lazy so keys that are never accessed again
  are still released from the cache.
- It does not acquire an exclusive lock on cache hits.
- It supports per entry ttls specified on Set.

The expiring cache (without striping) does somewhere in between the
simple cache and striped cache in the very contrived contention test
where every iteration acquires a write lock:

```
$ benchstat simple.log expiring.log
name      old time/op    new time/op    delta
Cache-12    2.74µs ± 2%    2.02µs ± 3%  -26.37%  (p=0.000 n=9+9)
name      old alloc/op   new alloc/op   delta
Cache-12      182B ± 0%      107B ± 4%  -41.21%  (p=0.000 n=8+9)
name      old allocs/op  new allocs/op  delta
Cache-12      5.00 ± 0%      2.00 ± 0%  -60.00%  (p=0.000 n=10+10)

$ benchstat striped.log expiring.log
name      old time/op    new time/op    delta
Cache-12    1.58µs ± 5%    2.02µs ± 3%  +27.34%  (p=0.000 n=10+9)
name      old alloc/op   new alloc/op   delta
Cache-12      288B ± 0%      107B ± 4%  -62.85%  (p=0.000 n=10+9)
name      old allocs/op  new allocs/op  delta
Cache-12      9.00 ± 0%      2.00 ± 0%  -77.78%  (p=0.000 n=10+10)

$ benchstat simple.log striped.log expiring.log
name \ time/op    simple.log   striped.log  expiring.log
Cache-12          2.74µs ± 2%  1.58µs ± 5%   2.02µs ± 3%
name \ alloc/op   simple.log   striped.log  expiring.log
Cache-12            182B ± 0%    288B ± 0%     107B ± 4%
name \ allocs/op  simple.log   striped.log  expiring.log
Cache-12            5.00 ± 0%    9.00 ± 0%     2.00 ± 0%
```

I also naively replacemed the LRU cache with the expiring cache in the
more realisitc CachedTokenAuthenticator benchmarks:

https://gist.github.com/mikedanese/41192b6eb62106c0758a4f4885bdad53

For token counts that fit in the LRU, expiring cache does better because
it does not require acquiring an exclusive lock for cache hits.

For token counts that exceed the size of the LRU, the LRU has a massive
performance drop off. The LRU cache is around 5x slower (with lookups
taking 1 milisecond and throttled to max 40 lookups in flight).

```
$ benchstat before.log after.log
name                                                  old time/op    new time/op    delta
CachedTokenAuthenticator/tokens=100_threads=256-12      3.60µs ±22%    1.08µs ± 4%  -69.91%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=500_threads=256-12      3.94µs ±19%    1.20µs ± 3%  -69.57%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=2500_threads=256-12     3.07µs ± 6%    1.17µs ± 1%  -61.87%  (p=0.000 n=9+10)
CachedTokenAuthenticator/tokens=12500_threads=256-12    3.16µs ±17%    1.38µs ± 1%  -56.23%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=62500_threads=256-12    15.0µs ± 1%     2.9µs ± 3%  -80.71%  (p=0.000 n=10+10)

name                                                  old alloc/op   new alloc/op   delta
CachedTokenAuthenticator/tokens=100_threads=256-12        337B ± 1%      300B ± 0%  -11.06%  (p=0.000 n=10+8)
CachedTokenAuthenticator/tokens=500_threads=256-12        307B ± 1%      304B ± 0%   -0.96%  (p=0.000 n=9+10)
CachedTokenAuthenticator/tokens=2500_threads=256-12       337B ± 1%      304B ± 0%   -9.79%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=12500_threads=256-12      343B ± 1%      276B ± 0%  -19.58%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=62500_threads=256-12      493B ± 0%      334B ± 0%  -32.12%  (p=0.000 n=10+10)

name                                                  old allocs/op  new allocs/op  delta
CachedTokenAuthenticator/tokens=100_threads=256-12        13.0 ± 0%      11.0 ± 0%  -15.38%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=500_threads=256-12        12.0 ± 0%      11.0 ± 0%   -8.33%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=2500_threads=256-12       13.0 ± 0%      11.0 ± 0%  -15.38%  (p=0.000 n=10+10)
CachedTokenAuthenticator/tokens=12500_threads=256-12      13.0 ± 0%      10.0 ± 0%  -23.08%  (p=0.000 n=9+10)
CachedTokenAuthenticator/tokens=62500_threads=256-12      17.0 ± 0%      12.0 ± 0%  -29.41%  (p=0.000 n=10+10)
```

Benchmarked with changes in #84423

Bugs: #83259 #83375

Kubernetes-commit: 9167711fd18511ffc9c90ee306c462be9fc7999b
This commit is contained in:
Mike Danese 2019-10-26 12:19:07 -07:00 committed by Kubernetes Publisher
parent 586878aa9d
commit f2f06b692c
2 changed files with 17 additions and 22 deletions

31
go.mod
View File

@ -36,14 +36,14 @@ require (
golang.org/x/sys v0.0.0-20190826190057-c7b8b68b1456
gopkg.in/yaml.v2 v2.2.4
gotest.tools v2.2.0+incompatible // indirect
k8s.io/api v0.0.0-20191115015536-da2cf76beda8
k8s.io/apimachinery v0.0.0-20191114215425-67a48e0c9266
k8s.io/cli-runtime v0.0.0-20191114223242-4080d562cce2
k8s.io/client-go v0.0.0-20191114220110-6f03b71b98e6
k8s.io/component-base v0.0.0-20191115015918-50dd3c3ffc6e
k8s.io/api v0.0.0
k8s.io/apimachinery v0.0.0
k8s.io/cli-runtime v0.0.0
k8s.io/client-go v0.0.0
k8s.io/component-base v0.0.0
k8s.io/klog v1.0.0
k8s.io/kube-openapi v0.0.0-20191107075043-30be4d16710a
k8s.io/metrics v0.0.0-20191114223047-4f433f22148a
k8s.io/metrics v0.0.0
k8s.io/utils v0.0.0-20191030222137-2b95a09bc58d
sigs.k8s.io/kustomize v2.0.3+incompatible
sigs.k8s.io/yaml v1.1.0
@ -51,13 +51,14 @@ require (
)
replace (
golang.org/x/sys => golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a // pinned to release-branch.go1.13
golang.org/x/tools => golang.org/x/tools v0.0.0-20190821162956-65e3620a7ae7 // pinned to release-branch.go1.13
k8s.io/api => k8s.io/api v0.0.0-20191115015536-da2cf76beda8
k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20191114215425-67a48e0c9266
k8s.io/cli-runtime => k8s.io/cli-runtime v0.0.0-20191114223242-4080d562cce2
k8s.io/client-go => k8s.io/client-go v0.0.0-20191114220110-6f03b71b98e6
k8s.io/code-generator => k8s.io/code-generator v0.0.0-20191114215150-2a85f169f05f
k8s.io/component-base => k8s.io/component-base v0.0.0-20191115015918-50dd3c3ffc6e
k8s.io/metrics => k8s.io/metrics v0.0.0-20191114223047-4f433f22148a
golang.org/x/sys => golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a
golang.org/x/tools => golang.org/x/tools v0.0.0-20190821162956-65e3620a7ae7
k8s.io/api => ../api
k8s.io/apimachinery => ../apimachinery
k8s.io/cli-runtime => ../cli-runtime
k8s.io/client-go => ../client-go
k8s.io/code-generator => ../code-generator
k8s.io/component-base => ../component-base
k8s.io/kubectl => ../kubectl
k8s.io/metrics => ../metrics
)

8
go.sum
View File

@ -115,6 +115,7 @@ github.com/google/gofuzz v1.0.0 h1:A8PeW59pxE9IoFRqBp37U+mSNaQoZ46F1f0f863XSXw=
github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
github.com/google/uuid v1.1.1 h1:Gkbcsh/GbpXz7lPftLA3P6TYMwjCLYm83jiFQZF/3gY=
github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
github.com/googleapis/gnostic v0.0.0-20170729233727-0c5108395e2d h1:7XGaL1e6bYS1yIonGp9761ExpPPV1ui0SAC59Yube9k=
@ -316,12 +317,6 @@ gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=
gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=
honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
honnef.co/go/tools v0.0.0-20190106161140-3f1c8253044a/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
k8s.io/api v0.0.0-20191115015536-da2cf76beda8/go.mod h1:TnwOuwwOmtUq5BythlhmbJs+lwQGEsSJ6N4S4ODl2m8=
k8s.io/apimachinery v0.0.0-20191114215425-67a48e0c9266/go.mod h1:dXFS2zaQR8fyzuvRdJDHw2Aerij/yVGJSre0bZQSVJA=
k8s.io/cli-runtime v0.0.0-20191114223242-4080d562cce2/go.mod h1:evYyWPXqE2Wiiqe8OW8S6wN3ho9Kje4Nj2+We7k3uOo=
k8s.io/client-go v0.0.0-20191114220110-6f03b71b98e6/go.mod h1:Hykx8A+UlxwDre3qJcqZPgCAZGjl9vNp6yc7SmfMQ1k=
k8s.io/code-generator v0.0.0-20191114215150-2a85f169f05f/go.mod h1:Vh0irzg7dL9pFS4c8hFsali5txtbmse3MFS4zEH7Thg=
k8s.io/component-base v0.0.0-20191115015918-50dd3c3ffc6e/go.mod h1:mGvZw6rGJi0lRK5Qn3KrpKMsz2SmgmRw9oQoA3xkE7U=
k8s.io/gengo v0.0.0-20190128074634-0689ccc1d7d6/go.mod h1:ezvh/TsK7cY6rbqRK0oQQ8IAqLxYwwyPxAX1Pzy0ii0=
k8s.io/gengo v0.0.0-20190822140433-26a664648505/go.mod h1:ezvh/TsK7cY6rbqRK0oQQ8IAqLxYwwyPxAX1Pzy0ii0=
k8s.io/klog v0.0.0-20181102134211-b9b56d5dfc92/go.mod h1:Gq+BEi5rUBO/HRz0bTSXDUcqjScdoY3a9IHpCEIOOfk=
@ -330,7 +325,6 @@ k8s.io/klog v1.0.0 h1:Pt+yjF5aB1xDSVbau4VsWe+dQNzA0qv1LlXdC2dF6Q8=
k8s.io/klog v1.0.0/go.mod h1:4Bi6QPql/J/LkTDqv7R/cd3hPo4k2DG6Ptcz060Ez5I=
k8s.io/kube-openapi v0.0.0-20191107075043-30be4d16710a h1:UcxjrRMyNx/i/y8G7kPvLyy7rfbeuf1PYyBf973pgyU=
k8s.io/kube-openapi v0.0.0-20191107075043-30be4d16710a/go.mod h1:1TqjTSzOxsLGIKfj0lK8EeCP7K1iUG65v09OM0/WG5E=
k8s.io/metrics v0.0.0-20191114223047-4f433f22148a/go.mod h1:9avWaTSXiK84X4JXH0cmL4SLGfbu3uBXW6G7iUlyR70=
k8s.io/utils v0.0.0-20191030222137-2b95a09bc58d h1:1P0iBJsBzxRmR+dIFnM+Iu4aLxnoa7lBqozW/0uHbT8=
k8s.io/utils v0.0.0-20191030222137-2b95a09bc58d/go.mod h1:sZAwmy6armz5eXlNoLmJcl4F1QuKu7sr+mFQ0byX7Ew=
modernc.org/cc v1.0.0/go.mod h1:1Sk4//wdnYJiUIxnW8ddKpaOJCF37yAdqYnkxUpaYxw=