From a4389fb761b670c6424ccd9fdb71d89dd7a46038 Mon Sep 17 00:00:00 2001
From: Jakob Ackermann <jakob.ackermann@overleaf.com>
Date: Wed, 23 Jun 2021 09:15:05 +0100
Subject: [PATCH 1/3] [misc] ContentCacheMetrics: log slow pdf caching
 performance

---
 services/clsi/app/js/ContentCacheMetrics.js | 26 +++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/services/clsi/app/js/ContentCacheMetrics.js b/services/clsi/app/js/ContentCacheMetrics.js
index f5f9188ddc..d2da9d8601 100644
--- a/services/clsi/app/js/ContentCacheMetrics.js
+++ b/services/clsi/app/js/ContentCacheMetrics.js
@@ -1,4 +1,20 @@
+const logger = require('logger-sharelatex')
 const Metrics = require('./Metrics')
+const os = require('os')
+
+let CACHED_LOAD = {
+  expires: -1,
+  load: [0, 0, 0]
+}
+function getSystemLoad() {
+  if (CACHED_LOAD.expires < Date.now()) {
+    CACHED_LOAD = {
+      expires: Date.now() + 10 * 1000,
+      load: os.loadavg()
+    }
+  }
+  return CACHED_LOAD.load
+}
 
 const ONE_MB = 1024 * 1024
 
@@ -20,6 +36,16 @@ function emitPdfCachingStats(stats, timings) {
       ? timings.compileE2E /
         (timings.compileE2E - timings['compute-pdf-caching'])
       : 1
+  if (fraction > 1.5) {
+    logger.warn(
+      {
+        stats,
+        timings,
+        load: getSystemLoad()
+      },
+      'slow pdf caching'
+    )
+  }
   Metrics.summary('overhead-compute-pdf-ranges', fraction * 100 - 100)
 
   // How does the hashing scale to pdf size in MB?

From 11a44ff07ce5b3b2cb053ac315b13d105a53d225 Mon Sep 17 00:00:00 2001
From: Jakob Ackermann <jakob.ackermann@overleaf.com>
Date: Wed, 23 Jun 2021 11:27:19 +0100
Subject: [PATCH 2/3] [misc] ContentCacheMetrics: apply review feedback: ignore
 fast compiles

Co-Authored-By: Brian Gough <brian.gough@overleaf.com>
---
 services/clsi/app/js/ContentCacheMetrics.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/services/clsi/app/js/ContentCacheMetrics.js b/services/clsi/app/js/ContentCacheMetrics.js
index d2da9d8601..5c54ba0861 100644
--- a/services/clsi/app/js/ContentCacheMetrics.js
+++ b/services/clsi/app/js/ContentCacheMetrics.js
@@ -36,7 +36,7 @@ function emitPdfCachingStats(stats, timings) {
       ? timings.compileE2E /
         (timings.compileE2E - timings['compute-pdf-caching'])
       : 1
-  if (fraction > 1.5) {
+  if (fraction > 1.5 && timings.compileE2E > 10 * 1000) {
     logger.warn(
       {
         stats,

From 97693b49c2a6cffc2899def1568915eec02da279 Mon Sep 17 00:00:00 2001
From: Jakob Ackermann <jakob.ackermann@overleaf.com>
Date: Wed, 23 Jun 2021 11:28:31 +0100
Subject: [PATCH 3/3] [ContentCacheMetrics] add new metric for absolute time
 spent in PDF.js

---
 services/clsi/app/js/ContentCacheMetrics.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/services/clsi/app/js/ContentCacheMetrics.js b/services/clsi/app/js/ContentCacheMetrics.js
index 5c54ba0861..0078406926 100644
--- a/services/clsi/app/js/ContentCacheMetrics.js
+++ b/services/clsi/app/js/ContentCacheMetrics.js
@@ -30,6 +30,9 @@ function emitPdfStats(stats, timings) {
 function emitPdfCachingStats(stats, timings) {
   if (!stats['pdf-size']) return // double check
 
+  // How much extra time did we spent in PDF.js?
+  Metrics.timing('compute-pdf-caching', timings['compute-pdf-caching'])
+
   // How large is the overhead of hashing up-front?
   const fraction =
     timings.compileE2E - timings['compute-pdf-caching'] !== 0