21227: Use a separate global requestLimiter for each target host.

[arvados.git] / sdk / go / arvados / client.go

diff --git a/sdk/go/arvados/client.go b/sdk/go/arvados/client.go
index 172763fe8065dda88f37ab9ffb011244f2a61d3a..8a7c7fa60f82d056c1198380cc01d11776d095d7 100644 (file)
--- a/sdk/go/arvados/client.go
+++ b/sdk/go/arvados/client.go
@@ -26,6 +26,7 @@ import (
        "regexp"
        "strconv"
        "strings"
+       "sync"
        "sync/atomic"
        "time"
 
@@ -356,17 +357,28 @@ func (c *Client) Last503() time.Time {
        return t
 }
 
-// globalRequestLimiter doesn't have a maximum number of outgoing
-// connections, but is just used to backoff after 503 errors.
-var globalRequestLimiter requestLimiter
+// globalRequestLimiter entries (one for each APIHost) don't have a
+// hard limit on outgoing connections, but do add a delay and reduce
+// concurrency after 503 errors.
+var (
+       globalRequestLimiter     = map[string]*requestLimiter{}
+       globalRequestLimiterLock sync.Mutex
+)
 
-// Get this client's requestLimiter, or the global requestLimiter
-// singleton if the client doesn't have its own.
+// Get this client's requestLimiter, or a global requestLimiter
+// singleton for c's APIHost if this client doesn't have its own.
 func (c *Client) getRequestLimiter() *requestLimiter {
        if c.requestLimiter != nil {
                return c.requestLimiter
        }
-       return &globalRequestLimiter
+       globalRequestLimiterLock.Lock()
+       defer globalRequestLimiterLock.Unlock()
+       limiter := globalRequestLimiter[c.APIHost]
+       if limiter == nil {
+               limiter = &requestLimiter{}
+               globalRequestLimiter[c.APIHost] = limiter
+       }
+       return limiter
 }
 
 // cancelOnClose calls a provided CancelFunc when its wrapped