net/http: increase panic stack trace buffer size from 4 KB to 64 KB.

4 KB is a bit too small in some situations (e.g. panic during a
template execution), and ends up with an unhelpfully-truncated trace.
64 KB should be much more likely to capture the useful information.
There's not a garbage generation issue, since this code should only
be triggered when there's something seriously wrong with the program.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://golang.org/cl/63520043

diff --git a/src/pkg/net/http/server.go b/src/pkg/net/http/server.go
index 77cbee1dee3ae45185195ab22652edce7cd97e3c..fea1898fd7e794c3e98f973808c931a9f2acb22e 100644 (file)
--- a/src/pkg/net/http/server.go
+++ b/src/pkg/net/http/server.go
@@ -1083,7 +1083,7 @@ func validNPN(proto string) bool {
 func (c *conn) serve() {
        defer func() {
                if err := recover(); err != nil {
-                       const size = 4096
+                       const size = 64 << 10
                        buf := make([]byte, size)
                        buf = buf[:runtime.Stack(buf, false)]
                        log.Printf("http: panic serving %v: %v\n%s", c.remoteAddr, err, buf)