From d5127b7d974e367137048f002257ab2532749fa9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adam=20Medzi=C5=84ski?= <medzin@users.noreply.github.com>
Date: Thu, 26 Apr 2018 07:30:15 +0200
Subject: [PATCH] Increase JSON scraper max buffer to 1MB (#112)

Sometimes applications, especially Java based, can produce huge log
lines. The executor does not use much memory so extra megabyte should
not be a problem and it gives us some reserve of memory (so we can
avoid some bufio.ErrTooLong errors). Default max buffer for
bufio.Scanner was 64 kilobytes.
---
 servicelog/scraper/json.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/servicelog/scraper/json.go b/servicelog/scraper/json.go
index 370b2c91..8d146b9e 100644
--- a/servicelog/scraper/json.go
+++ b/servicelog/scraper/json.go
@@ -11,6 +11,11 @@ import (
 	"github.com/allegro/mesos-executor/servicelog"
 )
 
+const (
+	kilobyte = 1024
+	megabyte = 1024 * kilobyte
+)
+
 // JSON is a scraper for logs represented as JSON objects.
 type JSON struct {
 	KeyFilter Filter
@@ -21,6 +26,7 @@ type JSON struct {
 // as the passed reader does not return an io.EOF error.
 func (j *JSON) StartScraping(reader io.Reader) <-chan servicelog.Entry {
 	scanner := bufio.NewScanner(reader)
+	scanner.Buffer(make([]byte, 64*kilobyte), megabyte)
 	logEntries := make(chan servicelog.Entry)
 
 	go func() {