1# Metrics Internals Debug Page 2 3**chrome://metrics-internals** is a debug page that reports the state of various 4metrics systems. 5 6The page displays logs that have been collected by the UMA metrics service, 7which are eventually sent to Google servers. These logs can be exported, and 8their proto data can later be inspected using a Google-internal tool: 9[go/metrics-internals-inspector](http://go/metrics-internals-inspector). 10 11On debug builds, the page will show all logs collected since browser startup, 12including logs from previous sessions that were not sent yet. On release builds, 13the page will instead show logs collected since the page was opened. This 14difference is mostly due to memory concerns (on official releases, we don't want 15logs to be lingering in memory since they can be relatively large). 16 17> Tip: By using the `--export-uma-logs-to-file=FILE_PATH` command line flag, all 18logs collected throughout the Chrome session will be exported to the passed 19`FILE_PATH` on shutdown (the file is created if it does not already exist). For 20release builds, this flag also has the effect of showing all logs collected 21since browser startup on the page. 22 23> Note: The delay between logs being closed can be [long]. If you are just 24testing to see if a certain metric (e.g., histogram, user action, etc.) is being 25properly sent to Google servers and you want logs to be collected more often, 26you can use the `--metrics-upload-interval=N` command line flag, where `N` is in 27seconds and is at least `20`. 28 29[long]: https://source.chromium.org/chromium/chromium/src/+/main:components/metrics/net/cellular_logic_helper.cc;l=18,21;drc=8ba1bad80dc22235693a0dd41fe55c0fd2dbdabd 30 31Unlike other metrics debug pages ([chrome://user-actions], **chrome://ukm**, and 32[chrome://histograms]), this page focuses mainly on what has actually been sent 33to Google servers. For example, it is possible that a user action shown on 34[chrome://user-actions] is never actually sent (e.g., due to being [truncated] 35for bandwidth reasons). Similarly, a source shown on **chrome://ukm** might be 36[dropped] and hence never be sent. Or, a histogram shown on 37[chrome://histograms] would not have been collected under regular circumstances 38(e.g., subprocess histograms, which are normally only collected periodically, 39but are collected [immediately] when loading **chrome://histograms**). In other 40words, this page displays the actual logs that have been created and sent, 41without modifications. 42 43[chrome://user-actions]: https://chromium.googlesource.com/chromium/src/+/master/tools/metrics/actions/README.md#Testing 44[chrome://histograms]: https://chromium.googlesource.com/chromium/src/+/master/tools/metrics/histograms/README.md#Testing 45[truncated]: https://source.chromium.org/chromium/chromium/src/+/main:components/metrics/metrics_log.cc;l=552;drc=38321ee39cd73ac2d9d4400c56b90613dee5fe29 46[dropped]: https://source.chromium.org/chromium/chromium/src/+/main:components/ukm/ukm_recorder_impl.cc;l=362;drc=38321ee39cd73ac2d9d4400c56b90613dee5fe29 47[immediately]: https://source.chromium.org/chromium/chromium/src/+/main:content/browser/metrics/histograms_internals_ui.cc;l=100;drc=5e521f43547ebdce502a555c5edb3a18f0c87a8a 48