To use pprof
to analyze performance and memory consumption in Envoy, you can
use the built-in statically linked profiler, or dynamically link it in to a
specific place yourself.
Static linking is already available (because of a HeapProfilerDump()
call
inside
Envoy::Profiler::Heap::stopProfiler())
).
Build the static binary using bazel:
$ bazel build //source/exe:envoy-static
And run the binary with a HEAPPROFILE
environment variable, like so:
$ HEAPPROFILE=/tmp/mybin.hprof bazel-bin/source/exe/envoy-static <args>
HEAPPROFILE
sets a location for the profiler output. A statically-linked
binary must be run with this environment variable; a dynamically-linked binary
will populate the working directory by default. (See Methodology.)
A statically-linked Envoy will profile everything. In a dynamically-linked
Envoy, you must add the HeapProfiler instructions yourself.
HeapProfilerStart()
will start recording allocations, HeapProfilerStop()
will stop recording, and HeapProfilerDump()
will dump an output to the
specified directory. (See Gperftools Heap
Profiler.)
To add a HeapProfiler
breakpoint yourself, add tcmalloc
as a
dependency under the envoy_cc_library
rule:
source/exe/BUILD
envoy_cc_library(
name = "envoy_common_lib",
+ tcmalloc_dep = 1,
deps = [
...
)
It is then necessary to add HeapProfilerStart()
and HeapProfilerDump()
breakpoints somewhere in Envoy. One place to start profiling is at the
instantiation of MainCommonBase::MainCommonBase
:
source/exe/main_common.cc
// includes
#include "gperftools/heap-profiler.h"
...
MainCommonBase::MainCommonBase(...) : ... {
+ HeapProfilerStart("main_common_base"); // first line
...
}
source/server/server.cc
// includes
#include "gperftools/heap-profiler.h"
...
void InstanceImpl::Initialize(...) : ... {
...
+ HeapProfilerDump("main_common_base"); // last line
}
Once these changes have been made in your working directory, it might make sense to
save the diff as a patch (git diff > file
), which can then be quickly
applied/unapplied for testing and committing. (git apply
, git apply -R
)
Build the binary using bazel, and run the binary without any environment variables:
$ bazel build //source/exe:envoy
$ bazel-bin/source/exe/envoy <args>
This will dump your profiler output to the working directory.
To support memory leaks detection, tests are built with gperftools dependencies enabled by default.
Use HeapProfilerStart()
, HeapProfilerStop()
, and HeapProfilerDump()
to start, stop, and persist
memory dumps, respectively. Please see above for more details.
By default, bazel executes tests in a sandbox, which will be deleted together with memory dumps
after the test run. To preserve memory dumps, bazel can be forced to run tests without
sandboxing, by setting the TestRunner
parameter to local
:
bazel test --strategy=TestRunner=local ...
An alternative is to set HEAPPROFILE
environment variable for the test runner:
bazel test --test_env=HEAPPROFILE=/tmp/testprofile ...
For consistent testing, it makes sense to run Envoy for a constant amount of time across trials:
$ timeout <num_seconds> bazel-bin/source/exe/envoy <options>
Envoy will print to stdout something like:
Starting tracking the heap
And then a series of stdouts like:
Dumping heap profile to <heap file 0001> (100 MB currently in use)
Dumping heap profile to <heap file 0002> (200 MB currently in use)
...
This will generate a series of files; if you statically-linked, these are
wherever HEAPPROFILE
points to. Otherwise, they are in the current directory
by default. They'll be named something like main_common_base.0001.heap
,
main_common_base.0002.heap
, etc.
NB: There is no reason this needs to be titled main_common_base
. Whatever
flag you supply HeapProfilerStart
/ HeapProfilerDump
will become the
filename. Multiple sections of code could be profiled simultaneously by setting
multiple HeapProfilerStart()
/ HeapProfilerStop()
breakpoints with unique
identifiers.
pprof can read these heap files in a
number of ways. Most convenient for first-order inspection might be pprof -top
or pprof -text
:
$ pprof -text bazel-bin/source/exe/envoy main_common_base* | head -n5
File: envoy
Build ID: ...
Type: inuse_space
Showing nodes accounting for 6402800.62kB, 98.59% of 6494044.58kB total
Dropped ... nodes (cum <= ...kB)
More complex flame/graph charts can be generated and viewed in a browser, which is often more helpful than text-based output:
$ pprof -http=localhost:9999 bazel-bin/source/exe/envoy main_common_base*