ProfileServlet.java
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.http;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.hadoop.thirdparty.com.google.common.base.Joiner;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.util.ProcessUtils;
/**
* Servlet that runs async-profiler as web-endpoint.
* <p>
* Following options from async-profiler can be specified as query paramater.
* // -e event profiling event: cpu|alloc|lock|cache-misses etc.
* // -d duration run profiling for 'duration' seconds (integer)
* // -i interval sampling interval in nanoseconds (long)
* // -j jstackdepth maximum Java stack depth (integer)
* // -b bufsize frame buffer size (long)
* // -t profile different threads separately
* // -s simple class names instead of FQN
* // -o fmt[,fmt...] output format: summary|traces|flat|collapsed|svg|tree|jfr|html
* // --width px SVG width pixels (integer)
* // --height px SVG frame height pixels (integer)
* // --minwidth px skip frames smaller than px (double)
* // --reverse generate stack-reversed FlameGraph / Call tree
* <p>
* Example:
* If Namenode http address is localhost:9870, and ResourceManager http address is localhost:8088,
* ProfileServlet running with async-profiler setup can be accessed with
* http://localhost:9870/prof and http://localhost:8088/prof for Namenode and ResourceManager
* processes respectively.
* Deep dive into some params:
* - To collect 10 second CPU profile of current process i.e. Namenode (returns FlameGraph svg)
* curl "http://localhost:9870/prof"
* - To collect 10 second CPU profile of pid 12345 (returns FlameGraph svg)
* curl "http://localhost:9870/prof?pid=12345" (For instance, provide pid of Datanode)
* - To collect 30 second CPU profile of pid 12345 (returns FlameGraph svg)
* curl "http://localhost:9870/prof?pid=12345&duration=30"
* - To collect 1 minute CPU profile of current process and output in tree format (html)
* curl "http://localhost:9870/prof?output=tree&duration=60"
* - To collect 10 second heap allocation profile of current process (returns FlameGraph svg)
* curl "http://localhost:9870/prof?event=alloc"
* - To collect lock contention profile of current process (returns FlameGraph svg)
* curl "http://localhost:9870/prof?event=lock"
* <p>
* Following event types are supported (default is 'cpu') (NOTE: not all OS'es support all events)
* // Perf events:
* // cpu
* // page-faults
* // context-switches
* // cycles
* // instructions
* // cache-references
* // cache-misses
* // branches
* // branch-misses
* // bus-cycles
* // L1-dcache-load-misses
* // LLC-load-misses
* // dTLB-load-misses
* // mem:breakpoint
* // trace:tracepoint
* // Java events:
* // alloc
* // lock
*/
@InterfaceAudience.Private
public class ProfileServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final Logger LOG = LoggerFactory.getLogger(ProfileServlet.class);
static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";
static final String ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin";
private static final String ALLOWED_METHODS = "GET";
private static final String CONTENT_TYPE_TEXT = "text/plain; charset=utf-8";
private static final String ASYNC_PROFILER_HOME_ENV = "ASYNC_PROFILER_HOME";
private static final String ASYNC_PROFILER_HOME_SYSTEM_PROPERTY = "async.profiler.home";
private static final String PROFILER_SCRIPT = "/profiler.sh";
private static final int DEFAULT_DURATION_SECONDS = 10;
private static final AtomicInteger ID_GEN = new AtomicInteger(0);
static final String OUTPUT_DIR = System.getProperty("java.io.tmpdir") + "/prof-output-hadoop";
// This flag is only allowed to be reset by tests.
private static boolean isTestRun = false;
private enum Event {
CPU("cpu"),
ALLOC("alloc"),
LOCK("lock"),
PAGE_FAULTS("page-faults"),
CONTEXT_SWITCHES("context-switches"),
CYCLES("cycles"),
INSTRUCTIONS("instructions"),
CACHE_REFERENCES("cache-references"),
CACHE_MISSES("cache-misses"),
BRANCHES("branches"),
BRANCH_MISSES("branch-misses"),
BUS_CYCLES("bus-cycles"),
L1_DCACHE_LOAD_MISSES("L1-dcache-load-misses"),
LLC_LOAD_MISSES("LLC-load-misses"),
DTLB_LOAD_MISSES("dTLB-load-misses"),
MEM_BREAKPOINT("mem:breakpoint"),
TRACE_TRACEPOINT("trace:tracepoint");
private final String internalName;
Event(final String internalName) {
this.internalName = internalName;
}
public String getInternalName() {
return internalName;
}
public static Event fromInternalName(final String name) {
for (Event event : values()) {
if (event.getInternalName().equalsIgnoreCase(name)) {
return event;
}
}
return null;
}
}
private enum Output {
SUMMARY,
TRACES,
FLAT,
COLLAPSED,
// No SVG in 2.x asyncprofiler.
SVG,
TREE,
JFR,
// In 2.x asyncprofiler, this is how you get flamegraphs.
HTML
}
private final Lock profilerLock = new ReentrantLock();
private transient volatile Process process;
private final String asyncProfilerHome;
private Integer pid;
public ProfileServlet() {
this.asyncProfilerHome = getAsyncProfilerHome();
this.pid = ProcessUtils.getPid();
LOG.info("Servlet process PID: {} asyncProfilerHome: {}", pid, asyncProfilerHome);
}
static void setIsTestRun(boolean isTestRun) {
ProfileServlet.isTestRun = isTestRun;
}
@Override
protected void doGet(final HttpServletRequest req, final HttpServletResponse resp)
throws IOException {
if (!HttpServer2.isInstrumentationAccessAllowed(getServletContext(), req, resp)) {
resp.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
setResponseHeader(resp);
resp.getWriter().write("Unauthorized: Instrumentation access is not allowed!");
return;
}
// make sure async profiler home is set
if (asyncProfilerHome == null || asyncProfilerHome.trim().isEmpty()) {
resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
setResponseHeader(resp);
resp.getWriter().write("ASYNC_PROFILER_HOME env is not set.\n\n"
+ "Please ensure the prerequisites for the Profiler Servlet have been installed and the\n"
+ "environment is properly configured.");
return;
}
// if pid is explicitly specified, use it else default to current process
pid = getInteger(req, "pid", pid);
// if pid is not specified in query param and if current process pid cannot be determined
if (pid == null) {
resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
setResponseHeader(resp);
resp.getWriter().write(
"'pid' query parameter unspecified or unable to determine PID of current process.");
return;
}
final int duration = getInteger(req, "duration", DEFAULT_DURATION_SECONDS);
final Output output = getOutput(req);
final Event event = getEvent(req);
final Long interval = getLong(req, "interval");
final Integer jstackDepth = getInteger(req, "jstackdepth", null);
final Long bufsize = getLong(req, "bufsize");
final boolean thread = req.getParameterMap().containsKey("thread");
final boolean simple = req.getParameterMap().containsKey("simple");
final Integer width = getInteger(req, "width", null);
final Integer height = getInteger(req, "height", null);
final Double minwidth = getMinWidth(req);
final boolean reverse = req.getParameterMap().containsKey("reverse");
if (process == null || !process.isAlive()) {
try {
int lockTimeoutSecs = 3;
if (profilerLock.tryLock(lockTimeoutSecs, TimeUnit.SECONDS)) {
try {
File outputFile = new File(OUTPUT_DIR,
"async-prof-pid-" + pid + "-" + event.name().toLowerCase() + "-" + ID_GEN
.incrementAndGet() + "." + output.name().toLowerCase());
List<String> cmd = new ArrayList<>();
cmd.add(asyncProfilerHome + PROFILER_SCRIPT);
cmd.add("-e");
cmd.add(event.getInternalName());
cmd.add("-d");
cmd.add("" + duration);
cmd.add("-o");
cmd.add(output.name().toLowerCase());
cmd.add("-f");
cmd.add(outputFile.getAbsolutePath());
if (interval != null) {
cmd.add("-i");
cmd.add(interval.toString());
}
if (jstackDepth != null) {
cmd.add("-j");
cmd.add(jstackDepth.toString());
}
if (bufsize != null) {
cmd.add("-b");
cmd.add(bufsize.toString());
}
if (thread) {
cmd.add("-t");
}
if (simple) {
cmd.add("-s");
}
if (width != null) {
cmd.add("--width");
cmd.add(width.toString());
}
if (height != null) {
cmd.add("--height");
cmd.add(height.toString());
}
if (minwidth != null) {
cmd.add("--minwidth");
cmd.add(minwidth.toString());
}
if (reverse) {
cmd.add("--reverse");
}
cmd.add(pid.toString());
if (!isTestRun) {
process = ProcessUtils.runCmdAsync(cmd);
}
// set response and set refresh header to output location
setResponseHeader(resp);
resp.setStatus(HttpServletResponse.SC_ACCEPTED);
String relativeUrl = "/prof-output-hadoop/" + outputFile.getName();
resp.getWriter().write("Started [" + event.getInternalName()
+ "] profiling. This page will automatically redirect to " + relativeUrl + " after "
+ duration + " seconds. "
+ "If empty diagram and Linux 4.6+, see 'Basic Usage' section on the Async "
+ "Profiler Home Page, https://github.com/jvm-profiling-tools/async-profiler."
+ "\n\nCommand:\n" + Joiner.on(" ").join(cmd));
// to avoid auto-refresh by ProfileOutputServlet, refreshDelay can be specified
// via url param
int refreshDelay = getInteger(req, "refreshDelay", 0);
// instead of sending redirect, set auto-refresh so that browsers will refresh
// with redirected url
resp.setHeader("Refresh", (duration + refreshDelay) + ";" + relativeUrl);
resp.getWriter().flush();
} finally {
profilerLock.unlock();
}
} else {
setResponseHeader(resp);
resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
resp.getWriter()
.write("Unable to acquire lock. Another instance of profiler might be running.");
LOG.warn("Unable to acquire lock in {} seconds. Another instance of profiler might be"
+ " running.", lockTimeoutSecs);
}
} catch (InterruptedException e) {
LOG.warn("Interrupted while acquiring profile lock.", e);
resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
} else {
setResponseHeader(resp);
resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
resp.getWriter().write("Another instance of profiler is already running.");
}
}
private Integer getInteger(final HttpServletRequest req, final String param,
final Integer defaultValue) {
final String value = req.getParameter(param);
if (value != null) {
try {
return Integer.valueOf(value);
} catch (NumberFormatException e) {
return defaultValue;
}
}
return defaultValue;
}
private Long getLong(final HttpServletRequest req, final String param) {
final String value = req.getParameter(param);
if (value != null) {
try {
return Long.valueOf(value);
} catch (NumberFormatException e) {
return null;
}
}
return null;
}
private Double getMinWidth(final HttpServletRequest req) {
final String value = req.getParameter("minwidth");
if (value != null) {
try {
return Double.valueOf(value);
} catch (NumberFormatException e) {
return null;
}
}
return null;
}
private Event getEvent(final HttpServletRequest req) {
final String eventArg = req.getParameter("event");
if (eventArg != null) {
Event event = Event.fromInternalName(eventArg);
return event == null ? Event.CPU : event;
}
return Event.CPU;
}
private Output getOutput(final HttpServletRequest req) {
final String outputArg = req.getParameter("output");
if (req.getParameter("output") != null) {
try {
return Output.valueOf(outputArg.trim().toUpperCase());
} catch (IllegalArgumentException e) {
return Output.HTML;
}
}
return Output.HTML;
}
static void setResponseHeader(final HttpServletResponse response) {
response.setHeader(ACCESS_CONTROL_ALLOW_METHODS, ALLOWED_METHODS);
response.setHeader(ACCESS_CONTROL_ALLOW_ORIGIN, "*");
response.setContentType(CONTENT_TYPE_TEXT);
}
static String getAsyncProfilerHome() {
String asyncProfilerHome = System.getenv(ASYNC_PROFILER_HOME_ENV);
// if ENV is not set, see if -Dasync.profiler.home=/path/to/async/profiler/home is set
if (asyncProfilerHome == null || asyncProfilerHome.trim().isEmpty()) {
asyncProfilerHome = System.getProperty(ASYNC_PROFILER_HOME_SYSTEM_PROPERTY);
}
return asyncProfilerHome;
}
}