tree d8e7a749d099dd12a1c6ce70a378634bbdd9c345
parent 3c2cc9a6329d9842b3bbdaf307a8110d740cf94c
author Dmitri Shuralyov <dmitshur@golang.org> 1589919483 -0400
committer Dmitri Shuralyov <dmitshur@golang.org> 1589928160 +0000

gddo-server: add a semaphore to limit concurrent graph requests

There should be an upper bound for the number of "dot" processes
that can be started concurrently in order to serve incoming HTTP
requests for the ?import-graph pages, to help avoid resource
exhaustion and server overload.

This change implements a limit of 10 such processes at once.

Change-Id: I65d01996461ae212bb84cfd8edfbe6fcec43c329
Reviewed-on: https://go-review.googlesource.com/c/gddo/+/234637
Reviewed-by: Robert Findley <rfindley@google.com>