Configure http2 with higher maxconcurrent streams (#7363)

This value is needed for Minio's internode communication,
read the meaning of this value as per the HTTP 2.0 spec

https://http2.github.io/http2-spec/#rfc.section.5.1.2

vendor/golang.org/x/net/http2/pipe.go

@@ -15,8 +15,8 @@ import (
 // underlying buffer is an interface. (io.Pipe is always unbuffered)
 type pipe struct {
 	mu       sync.Mutex
-	c        sync.Cond // c.L lazily initialized to &p.mu
-	b        pipeBuffer
+	c        sync.Cond     // c.L lazily initialized to &p.mu
+	b        pipeBuffer    // nil when done reading
 	err      error         // read error once empty. non-nil means closed.
 	breakErr error         // immediate read error (caller doesn't see rest of b)
 	donec    chan struct{} // closed on error
@@ -32,6 +32,9 @@ type pipeBuffer interface {
 func (p *pipe) Len() int {
 	p.mu.Lock()
 	defer p.mu.Unlock()
+	if p.b == nil {
+		return 0
+	}
 	return p.b.Len()
 }
 
@@ -47,7 +50,7 @@ func (p *pipe) Read(d []byte) (n int, err error) {
 		if p.breakErr != nil {
 			return 0, p.breakErr
 		}
-		if p.b.Len() > 0 {
+		if p.b != nil && p.b.Len() > 0 {
 			return p.b.Read(d)
 		}
 		if p.err != nil {
@@ -55,6 +58,7 @@ func (p *pipe) Read(d []byte) (n int, err error) {
 				p.readFn()     // e.g. copy trailers
 				p.readFn = nil // not sticky like p.err
 			}
+			p.b = nil
 			return 0, p.err
 		}
 		p.c.Wait()
@@ -75,6 +79,9 @@ func (p *pipe) Write(d []byte) (n int, err error) {
 	if p.err != nil {
 		return 0, errClosedPipeWrite
 	}
+	if p.breakErr != nil {
+		return len(d), nil // discard when there is no reader
+	}
 	return p.b.Write(d)
 }
 
@@ -109,6 +116,9 @@ func (p *pipe) closeWithError(dst *error, err error, fn func()) {
 		return
 	}
 	p.readFn = fn
+	if dst == &p.breakErr {
+		p.b = nil
+	}
 	*dst = err
 	p.closeDoneLocked()
 }