breadcrumbs: For Developers > page_name: deep-memory-profiler title: Deep Memory Profiler
The Deep Memory Profiler tools (dmprof) were not maintained, became non-functional, and were removed from the codebase . See issue 490464.
Deep Memory Profiler (dmprof) is a 1) whole-process, 2) timeline-based and 3) post-mortem memory profiler for Chromium. It's designed to categorize all memory usage in a process without any omission. See the Design Doc if interested.
Memory bloat has been a serious issue in Chromium for years. Bloat is harder to fix than leak and errors. We have memory checkers like Valgrind and Address Sanitizer for leak and errors, but no handy tools for bloat. Dmprof is an easy-to-use tool for bloat to know “who is the memory eater”. (It would be helpful also for leak.)
Future announcements (e.g. command line changes) will be done in dmprof@chromium.org. Subscribe it if you're interested.
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Dmprof profiles memory usage post-mortem. You need to 1) get memory dumps while Chrome is running, and then 2) analyze the dumps. The analyzing script dmprof is available in src/tools/deep_memory_profiler of the Chromium source tree, or can be retrieved by downloading and running download.sh.
You can use dmprof for Chromium static builds with some build options both for Release and Debug builds. Note that it is not available for shared builds.
Be careful not to overwrite GYP_DEFINES predefined by env_setup.sh.
Run Chromium with a command-line option --no-sandbox and the following environment variables:
$ HEAPPROFILE=$HOME/prof/prefix HEAP_PROFILE_TIME_INTERVAL=20 HEAP_PROFILE_MMAP=1 DEEP_HEAP_PROFILE=1 out/Release/chrome --no-sandbox
# NOTE: the device needs to be rooted! adb root # Create a world-writable dump directory adb shell mkdir -p /data/local/tmp/heap adb shell chmod 0777 /data/local/tmp/heap # Set the following system properties adb shell setprop heapprof /data/local/tmp/heap/dumptest adb shell setprop heapprof.mmap 1 adb shell setprop heapprof.deep_heap_profile 1 adb shell setprop heapprof.time_interval 10
Prepare a file /var/tmp/deep_memory_profiler_prefix.txt in your device or VM image. Its content should just have a prefix to dumped files /path/to/prefix like:
/var/tmp/heapprof
If you get dumps from a standalone Chromium process periodically, prepare a file /var/tmp/deep_memory_profiler_time_interval.txt which contains just an integer meaning the interval time to dump:
60
If you specified “time interval” described above, the Chromium process dumps heap profiles periodically. It depends on the platform how to specify “time interval”.
A WebDriver (ChromeDriver) API function is available to dump. Try dump_heap_profile():
dump_heap_profile(reason='Why you want a dump.')
Note that you may want to copy the dumps from your remote machine if you run ChromeDriver remotely.
You can dump heap profiles manually from DevTools (or automatically with your script) when you set the environment variables above and specify the command line option --enable-memory-benchmarking to Chrome.
chrome.memoryBenchmarking.heapProfilerDump("browser" or "renderer", "some reason")
You can use a Telemetry profiler to drive chrome and, if running on android, to also fetch the files from the device. It utilizes the above Memory Benchmarking V8 API internally. See Telemetry instructions.
Find the dumps at /path/to/prefix.*.heap as specified above. Names of the dumps include Process IDs. For example, prefix.12345.0002.heap for pid = 12345. ‘0002’ is a sequence number of the dump.
The dmprof analyzer script (in the Phase 5) needs the executed Chrome binary to extract symbols. If you analyze in the same host with the Chrome process, you don‘t need special things. If you analyze in a different host from the Chrome process (it’s common in Android and ChromeOS), you may need to specify the path to the executed Chrome binary on the host. (See Phase 5 for details.)
Heap profiles are dumped to the directory where you specified in the environment variable HEAPPROFILE.
Heap profiles are dumped in the device directory where you specified in the property heapprof. Fetch the dump from the device to your host by the following command.
adb pull /data/local/tmp/heap/ .
The dmprof script guesses the path of the Chrome binary on the host if the executed binary was in an Android-specific directory (e.g. /data/app-lib/). If the guess fails, use --alternative-dirs for the dmprof script (in the Phase 5).
Heap profiles are dumped in the device directory where you specified in /var/tmp/deep_memory_profiler_prefix.txt. Fetch them in a certain way like scp from the device / VM.
The dmprof script doesn't know where is the Chrome binary on the host. Use --alternative-dirs for the dmprof script (in the Phase 5).
Use the dmprof script to analyze with the dumped heap profiles.
$ dmprof csv dmprof.03511.0001.heap > dmprof.03511.result.csv
Or, use this to generate a local html with a graph and a data table:
# Generate a JSON output for your dumps. $ tools/deep_memory_profiler/dmprof json /path/to/first-one-of-the-dumps.heap > FOO.json # Convert the JSON file to a HTML file. $ tools/deep_memory_profiler/graph.py FOO.json > graph.html
In case of Android or ChromeOS, you may need to use --alternative-dirs for the dmprof script to specify the path of the Chrome binary on the host instead of the path on the device.
$ dmprof csv --alternative-dirs=/data/app-lib/com.google.android.apps.chrome-1@/home/self/chrome/src/out/Release/lib dmprof.03511.0001.heap Assuming /data/app-lib/com.google.android.apps.chrome-1 on device as /home/self/chrome/src/out/Release/lib on host ...
$ dmprof csv --alternative-dirs=/opt/google/chrome@/home/self/chromeos/chroot/build/x86-generic/opt/google/chrome dmprof.03511.0001.heap Assuming /opt/google/chrome on device as /home/self/chromeos/chroot/build/x86-generic/opt/google/chrome on host ...
Given a specific component listed in the graph above, sue the following command to
tools/deep_memory_profiler/dmprof expand HEAP_FILE POLICY COMPONENT 32
## Caveats ### Linux / ChromeOS / Android * The total size can be different from RSS reported by ps and /proc/.../stat iin some cases. * RSS by ps and stat doesn't include a part of memory usage. For example, the page tables, kernel stack, struct thread_info, and struct task_struct (from man ps). The same difference is in smaps and pmap. * Deep Memory Profiler can double-count page frames (physical pages) which are mapped from different virtual pages in the same process. It hardly happens in Chrome. ## How to read the graph Graphs are typical stacked ones which classifies all memory usage into some components. We have four kinds of graphs from each execution dump based on four built-in "policies": l0, l1, l2, t0. We're preparing more breakdown policies. If you'd like to add a criteria for your component, 1) modify policy.\*.json files, 2) modify polices.json and add a policy file or 3) report it to dmprof@chromium.org. **Common components** mustbezero & unhooked-absent Should be zero. unhooked-anonymous VMA is mapped, but no information is recorded. No label is given in /proc/.../maps. unhooked-file-exec VMA is mapped, but no information is recorded. An executable file is mapped. unhooked-file-nonexec VMA is mapped, but no information is recorded. A non-executable file is mapped. unhooked-file-stack VMA is mapped, but no information is recorded. Used as a stack. unhooked-other VMA is mapped, but no information is recorded. Used for other purposes. no-bucket Should be small. Out of record because it is an ignorable small blocks. tc-unused Reserved by TCMalloc, but not used by malloc(). Headers, fragmentation and free-list. **Policy "l0"** This policy applies the most rough classification. mmap-v8 mmap'ed for V8. It includes JavaScript heaps and JIT compiled code. mmap-catch-all mmap'ed for other purposes. tc-used-all All memory blocks allocated by malloc(). **Policy "l1"** It breaks down memory usage into relatively specific components. mmap-v8-heap-newspace JavaScript new (nursery) heap for younger objects. mmap-v8-heap-coderange Code produced at runtime including JIT-compiled JavaScript code. mmap-v8-heap-pagedspace JavaScript old heap and many other object spaces. mmap-v8-other Other regions mmap'ed by V8. mmap-catch-all Any other mmap'ed regions. tc-v8 Blocks allocated from V8. tc-skia Blocks allocated from Skia. tc-webkit-catch-all Blocks allocated from WebKit. tc-unknown-string Blocks which are related to std::string. tc-catch-all Any other blocks allocated by malloc(). **Policy "l2"** It tries to breakdown memory usage into specific components. See [policy.l2.json](http://src.chromium.org/viewvc/chrome/trunk/src/tools/deep_memory_profiler/policy.l2.json?view=markup) for details, and report to dmprof@chromium.org to add more components. mmap-v8-heap-newspace JavaScript new (nursery) heap for younger objects. mmap-v8-heap-coderange Code produced at runtime including JIT-compiled JavaScript code. mmap-v8-heap-pagedspace JavaScript old heap and many other spaces. mmap-v8-other Other regions mmap'ed by V8. mmap-catch-all Any other mmap'ed regions. tc-webcore-fontcache Blocks used for FontCache. tc-skia Blocks used for Skia. tc-renderobject Blocks used for RenderObject. tc-renderstyle Blocks used for RenderStyle. tc-webcore-sharedbuf Blocks used for WebCore's SharedBuffer. tc-webcore-XHRcreate Blocks used for WebCore's XMLHttpRequest (create). tc-webcore-XHRreceived Blocks used for WebCore's XMLHttpRequest (received). tc-webcore-docwriter-add Blocks used for WebCore's DocumentWriter. tc-webcore-node-and-doc Blocks used for WebCore's HTMLElement, Text, and other Node objects. tc-webcore-node-factory Blocks created by WebCore's HTML\*Factory. tc-webcore-element-wrapper Blocks created by WebCore's createHTML\*ElementWrapper. tc-webcore-stylepropertyset Blocks used for WebCore's StylePropertySet (CSS). tc-webcore-style-createsheet Blocks created by WebCore's StyleElement::createSheet. tc-webcore-cachedresource Blocks used for WebCore's CachedResource. tc-webcore-script-execute Blocks created by WebCore's ScriptElement::execute. tc-webcore-events-related Blocks related to WebCore's events (EventListener and so on) tc-webcore-document-write Blocks created by WebCore's Document::write. tc-webcore-node-create-renderer Blocks created by WebCore's Node::createRendererIfNeeded. tc-webcore-render-catch-all Any other blocks related to WebCore's Render. tc-webcore-setInnerHTML-except-node Blocks created by setInnerHTML. tc-wtf-StringImpl-user-catch-all Blocks used for WTF::StringImpl. tc-wtf-HashTable-user-catch-all Blocks used for WTF::HashTable. tc-webcore-everything-create Blocks created by WebCore's any create() method. tc-webkit-from-v8-catch-all Blocks created by V8 via WebKit functions. tc-webkit-catch-all Any other blocks created by WebKit. tc-v8-catch-all Any other blocks created in V8. tc-toplevel-string All std::string objects created at the top-level. tc-catch-all Any other blocks by malloc(). **Policy "t0"** It classifies memory blocks based on their type_info. mmap-v8 mmap'ed for V8. It includes JavaScript heaps and JIT compiled code. mmap-catch-all mmap'ed for other purposes. tc-std-string std::string objects. tc-WTF-String WTF::String objects. tc-no-typeinfo-StringImpl No type_info (not allocated by 'new'), but allocated for StringImpl. tc-Skia Skia objects. tc-WebCore-Style WebCore's style objects. tc-no-typeinfo-other Any other blocks without type_info. tc-other All objects with other type_info. ## Cases * <http://crrev.com/166963>