diff --git a/services/track-changes/app/coffee/PackManager.coffee b/services/track-changes/app/coffee/PackManager.coffee
index 43de0dfc87..3311dbbb5a 100644
--- a/services/track-changes/app/coffee/PackManager.coffee
+++ b/services/track-changes/app/coffee/PackManager.coffee
@@ -2,6 +2,8 @@ async = require "async"
 _ = require "underscore"
 {db, ObjectId} = require "./mongojs"
 BSON=db.bson.BSON
+logger = require "logger-sharelatex"
+LockManager = require "./LockManager"
 
 module.exports = PackManager =
 	# The following functions implement methods like a mongo find, but
@@ -325,26 +327,101 @@ module.exports = PackManager =
 
 	insertPack: (packObj, callback) ->
 		bulk = db.docHistory.initializeOrderedBulkOp()
+		doc_id = packObj.doc_id
 		expect_nInserted = 1
 		expect_nRemoved = packObj.pack.length
+		logger.log {doc_id: doc_id}, "adding pack, removing #{expect_nRemoved} ops"
 		bulk.insert packObj
 		packObj.pack.forEach (op) ->
 			bulk.find({_id:op._id}).removeOne()
 		bulk.execute (err, result) ->
 			if err?
+				logger.error {doc_id: doc_id}, "error adding pack"
 				callback(err, result)
 			else if result.nInserted != expect_nInserted or result.nRemoved != expect_nRemoved
+				logger.error {doc_id: doc_id, result}, "unexpected result adding pack"
 				callback(new Error(
 					msg: 'unexpected result'
 					expected: {expect_nInserted, expect_nRemoved}
 				), result)
 			else
-				db.docHistoryStats.update {doc_id:packObj.doc_id}, {
+				db.docHistoryStats.update {doc_id:doc_id}, {
 					$inc:{update_count:-expect_nRemoved},
 					$currentDate:{last_packed:true}
 				}, {upsert:true}, () ->
 					callback(err, result)
 
+	# retrieve document ops/packs and check them
+	getDocHistory: (doc_id, callback) ->
+		db.docHistory.find({doc_id:ObjectId(doc_id)}).sort {v:1}, (err, docs) ->
+			return callback(err) if err?
+			# for safety, do a consistency check of the history
+			logger.log {doc_id}, "checking history for document"
+			PackManager.checkHistory docs, (err) ->
+				return callback(err) if err?
+				callback(err, docs)
+				#PackManager.deleteExpiredPackOps docs, (err) ->
+				#	return callback(err) if err?
+				#	callback err, docs
+
+	packDocHistory: (doc_id, options, callback) ->
+		if typeof callback == "undefined" and typeof options == 'function'
+			callback = options
+			options = {}
+		LockManager.runWithLock(
+			"HistoryLock:#{doc_id}",
+			(releaseLock) ->
+				PackManager._packDocHistory(doc_id, options, releaseLock)
+			,	callback
+		)
+
+	_packDocHistory: (doc_id, options, callback) ->
+		logger.log {doc_id},"starting pack operation for document history"
+
+		PackManager.getDocHistory doc_id, (err, docs) ->
+			return callback(err) if err?
+			origDocs = 0
+			origPacks = 0
+			for d in docs
+				if d.pack? then	origPacks++	else origDocs++
+			PackManager.convertDocsToPacks docs, (err, packs) ->
+				return callback(err) if err?
+				total = 0
+				for p in packs
+					total = total + p.pack.length
+				logger.log {doc_id, origDocs, origPacks, newPacks: packs.length, totalOps: total}, "document stats"
+				if packs.length
+					if options['dry-run']
+						logger.log {doc_id}, 'dry-run, skipping write packs'
+						return callback()
+					PackManager.savePacks packs, (err) ->
+						return callback(err) if err?
+						# check the history again
+						PackManager.getDocHistory doc_id, callback
+				else
+					logger.log {doc_id}, "no packs to write"
+					# keep a record that we checked this one to avoid rechecking it
+					db.docHistoryStats.update {doc_id:doc_id}, {
+						$currentDate:{last_checked:true}
+					}, {upsert:true}, () ->
+						callback null, null
+
+	DB_WRITE_DELAY: 2000
+
+	savePacks: (packs, callback) ->
+		async.eachSeries packs, PackManager.safeInsert, (err, result) ->
+			if err?
+				logger.log {err, result}, "error writing packs"
+				callback err, result
+			else
+				callback()
+
+	safeInsert: (packObj, callback) ->
+		PackManager.insertPack packObj, (err, result) ->
+			setTimeout () ->
+				callback(err,result)
+			, PackManager.DB_WRITE_DELAY
+
 	deleteExpiredPackOps: (docs, callback) ->
 		now = Date.now()
 		toRemove = []
diff --git a/services/track-changes/pack.coffee b/services/track-changes/pack.coffee
deleted file mode 100644
index 59e64aadf4..0000000000
--- a/services/track-changes/pack.coffee
+++ /dev/null
@@ -1,134 +0,0 @@
-Settings = require "settings-sharelatex"
-fs = require("fs")
-{db, ObjectId} = require "./app/coffee/mongojs"
-async = require("async")
-BSON=db.bson.BSON
-util = require 'util'
-_ = require 'underscore'
-PackManager = require "./app/coffee/PackManager.coffee"
-
-lineReader = require "line-reader"
-cli = require "cli"
-options = cli.parse {
-	'update': ['u', 'find documents to pack from database']
-	'dry-run':   ['n', 'do not write to database'],
-	'fast':  [false, 'no delays on writes']
-}
-
-DB_WRITE_DELAY = if options.fast then 0 else 2000
-DOCUMENT_PACK_DELAY = if options.fast then 0 else 1000
-
-packDocHistory = (doc_id, callback) ->
-	util.log "starting pack operation for #{doc_id}"
-	getDocHistory doc_id, (err, docs) ->
-		return callback(err) if err?
-		origDocs = 0
-		origPacks = 0
-		for d in docs
-			if d.pack? then	origPacks++	else origDocs++
-		PackManager.convertDocsToPacks docs, (err, packs) ->
-			return callback(err) if err?
-			total = 0
-			for p in packs
-				total = total + p.pack.length
-			util.log "docs #{origDocs} packs #{origPacks} => packs #{packs.length} of #{total} ops"
-			if packs.length
-				if options['dry-run']
-					util.log 'dry-run, skipping write packs'
-					return callback()
-				savePacks packs, (err) ->
-					return callback(err) if err?
-					# check the history again
-					getDocHistory doc_id, callback
-			else
-				util.log "no packs to write"
-				callback null, null
-
-# retrieve document ops/packs and check them
-getDocHistory = (doc_id, callback) ->
-	db.docHistory.find({doc_id:ObjectId(doc_id)}).sort {v:1}, (err, docs) ->
-		return callback(err) if err?
-		# for safety, do a consistency check of the history
-		util.log "checking history for #{doc_id}"
-		PackManager.checkHistory docs, (err) ->
-			return callback(err) if err?
-			callback(err, docs)
-			#PackManager.deleteExpiredPackOps docs, (err) ->
-			#	return callback(err) if err?
-			#	callback err, docs
-
-safeInsert = (packObj, callback) ->
-	if shutdownRequested
-		return callback('shutdown')
-	PackManager.insertPack packObj, (err, result) ->
-		setTimeout () ->
-			callback(err,result)
-		, DB_WRITE_DELAY
-
-savePacks = (packs, callback) ->
-	async.eachSeries packs, safeInsert, (err, result) ->
-		if err?
-			util.log "error writing packs"
-			callback err, result
-		else
-			util.log "done writing packs"
-			callback()
-
-readFile = (file, callback) ->
-	ids = []
-	lineReader.eachLine file, (line) ->
-		result = line.match(/[0-9a-f]{24}/)
-		if result?
-			ids.push result[0]
-	.then () ->
-		callback(null, ids)
-
-shutdownRequested = false
-process.on  'SIGINT', () ->
-	util.log "Gracefully shutting down from SIGINT"
-	shutdownRequested = true
-
-processUpdates = (pending) ->
-	async.eachSeries pending,	(doc_id, callback) ->
-		packDocHistory doc_id, (err, result) ->
-			if err?
-				console.log "ERROR:", err, result
-				return callback(err)
-			else if not options['dry-run'] && doneFile?
-				fs.appendFileSync doneFile, doc_id + '\n'
-			if shutdownRequested
-				return callback('shutdown')
-			setTimeout () ->
-				callback(err, result)
-			, DOCUMENT_PACK_DELAY
-	, (err, results) ->
-		if err?
-			console.log 'error:', err
-		util.log 'closing db'
-		db.close()
-
-if options['update']
-	util.log 'checking for updates'
-	db.docHistoryStats.find({
-		update_count: {$gt : PackManager.MIN_COUNT}
-	}).sort({
-		update_count:-1
-	}).limit 1000, (error, results) ->
-		if err?
-			utils.log 'error', error
-			db.close()
-			return
-		util.log "found #{results.length} documents to pack"
-		pending = _.pluck results, 'doc_id'
-		processUpdates pending
-else
-	todoFile = cli.args[1]
-	doneFile = cli.args[2]
-	util.log "reading from #{todoFile}"
-	util.log "logging progress to #{doneFile}"
-	fs.appendFileSync doneFile, '# starting pack run at ' + new Date() + '\n'
-
-	readFile todoFile, (err, todo) ->
-		readFile doneFile, (err, done) ->
-			pending = _.difference todo, done
-			processUpdates pending