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Using DTrace to Instrument Your System

Max Bruning, Training Director, Joyent

Wednesday, March 26, 14

Topics Covered

• DTrace

• What it does.

• Uses

• How Instruments uses it

• Examples


Tools Used in This Talk• DTrace

• Allows runtime observability into entire software stack

• Instruments

• performance, analysis, and testing tool for dynamically tracing and profiling OS X and iOS code

• Many of the instruments tools use DTrace (some use llvm)


What is DTrace?• Tool that allows one to dynamically instrument code from application level and into the

kernel.

• Can be used safely on production systems.

• Uses:

• Performance Analysis

• Debugging

• Code coverage

• Find out what is happening in your software

• Available on OS X, SmartOS, illumos, *BSD, Solaris and derivatives.

• Useful with C, Objective-C, C++, as well as higher level languages (java, perl, node, python, etc.).


Terminology•Probe - An instrumentation point in the code

•Dynamic and Static probes are provided, and new ones can be added

•A probe is specified by a 4-tuple:

•provider:module:function:probename{action}

•Action - Executed when a probe fires

•Predicate - Optional boolean to determine whether or not to execute the action

•Example: syscall::read:entry/pid == 713/{trace();}


Some Simple Examples•Show system calls made by a running process# dtrace -n ‘syscall:::entry/pid==26442/{}’dtrace: description 'syscall:::entry' matched 234 probesCPU ID FUNCTION:NAME 1 10157 write:entry 1 10155 read:entry 4 10155 read:entry ...

# dtrace -n 'syscall:::entry/execname == "Safari"/{@[probefunc]=count();}'dtrace: description 'syscall:::entry' matched 456 probes(^C)... mmap 183 psynch_mutexdrop 470 psynch_mutexwait 470 kevent64 6149 workq_kernreturn 6326

• Count system calls made by a running safari process


An Example MeasuringSystem Call Latency•systime.d

#!/usr/sbin/dtrace -s

#pragma D option quiet

syscall:::entry/execname == "node"/{ self->ts = timestamp;}

syscall:::return/self->ts/{ @[probefunc] = quantize(timestamp - self->ts); self->ts = 0;}

END{

! printa("SYSCALL NSECS # OF OCCURANCES\n%s%@lx\n", @);}


An Example MeasuringSystem Call Latency (Continued) # ./systime.d

...SYSCALL NSECS # OF OCCURANCES read value ------------- Distribution ------------- count 1024 | 0 2048 |@@@@@@@@@@@@@ 3 4096 |@@@@@@@@@ 2 8192 |@@@@@@@@@ 2 16384 |@@@@ 1 32768 | 0 ... 33554432 | 0 67108864 | 0 134217728 |@@@@ 1 268435456 | 0

...


DTrace Providers for OS X# dtrace -l | grep -v PROVIDER | awk '{print $2}' | sort -u | sed -e 's/[0-9].*//' | uniq | paste - - - - | awk '{ printf "%20-s %20-s %20-s %20-s\n", $1, $2, $3, $4 }'AppContainer AppSandbox Cocoa_Autorelease Cocoa_Layout CoreData CoreImage CoreText HALC_IO HALS_Engine HALS_IO HALS_System JavaScriptCore MetadataFramework MetadataImporter MobileDevice NSApplication NSTrackingArea NSXPCConnection NSXPCListener NSXPCProxy PDEProbes PMTiming PackageKit PrintCore QLSeamlessClosing QLSeamlessOpening QLThumbnail QuartzComposer QuickTimeX RawCamera RemoteViewServices SoftwareUpdate Suggestions afc cache codesign dtrace fbt garbage_collection io ip ldap_rb_stats lockstat mach_trap magmalloc mds node objc_runtime odprobes opencl_api opencl_cpu perl pid plockstat proc profile sched sdt security_debug security_exception security_machserver securityd syscall syspolicy tcp vminfo

• Providers not in grey are OS X specific (?)• More providers may exist, and more can be added


Instruments

• Performance, analysis, and testing tool for dynamically tracing and profiling OS X and iOS code

• Many of the instruments tools use DTrace (some use llvm)

• Instruments provides a GUI for implementing your own instruments using DTrace


Instruments and DTraceInstruments using Dtrace Sudden termination, Carbon Events, Core Data Saves/

Fetches/Faults, Cocoa Events/Layout, File Locks/Attributes, File Activity, Directory I/O, Garbage Collection, Reads/Writes, Shared Memory, Process, Custom Instruments

Instruments that Could be

implemented using DTrace

Time Profiler, Network Activity Monitor, Sampler, Memory/Disk/CPU/Activity Monitor, Thread States, VM Operations, System Calls, Scheduling


Example Instrument -File Activity


Example Instrument -File Activity (Continued)

• Edit as needed andsave or cancel.


Example Instrument -File Activity (Continued)


Example Instrument - DTrace Script$ cat fileact.d

#!/bin/bash## To run this script, please type the following command while in the same# directory (or specify the full path rather than './'):## sudo ./fileact.d -o dtrace_output.txt ## After the output file has been generated (here, it's dtrace_output.txt but you# may call it whatever you like), call up the trace document where# this script was exported from and choose the "DTrace Data Import..." option# from the "File" pulldown menu to import that data.#TOOLCHAINS=default/usr/sbin/dtrace $* -C -Z -s /dev/stdin << "End-Of-File"

#pragma D option switchrate=1msec...


Example Instrument -Running the D Script

$ sudo ./fileact.d -o fileact.out

•Run your workload while this is running•When ready, control-c or kill•Import fileact.out into Instruments•Modifying the script outside of Instruments may cause output to not be importable•Importing of arbitrary D script output into Instruments does not work


Example Instrument -D Script Output

<dtrace_output_begin/> 13953633063646380003A85E3B6-1514-4ECC-8EC8-40FB699DCAF9<e> -1 4 2 1246115 1395363306366033000fstat64dtrace6 </e><s>

libsystem_kernel.dylib`fstat$INODE64+0xalibsystem_c.dylib`__smakebuf+0x2alibsystem_c.dylib`__swsetup+0x84libsystem_c.dylib`__v2printf+0x55libsystem_c.dylib`__xvprintf+0x279libsystem_c.dylib`vfprintf+0x49libdtrace.dylib`dt_printf+0xf9libdtrace.dylib`dt_printf_format+0x19clibdtrace.dylib`dtrace_fprintf+0x33libdtrace.dylib`dt_consume_cpu+0xc47

libdtrace.dylib`dtrace_consume+0x3cblibdtrace.dylib`dtrace_work+0x7adtrace`main+0x1c9clibdyld.dylib`start+0x1dtrace`0x7</s><e> -1 6 6 1246115 1395363306367047000stat64dtrace/Library/Symbols </e><s>

libsystem_kernel.dylib`stat$INODE64+0xa...


Example D ScriptThat “mimics” Time Profiler

#!/usr/sbin/dtrace -qsBEGIN{ printf("%-24s %-8s %-16s %-24s %-24s\n", "Timestamp", "Depth", "Process", "Hot Frame", "Caller");}profile-1ms/arg0/{ printf("%-24Y %-8d %-16s %-24p %-24p\n", walltimestamp, stackdepth, execname, arg0, caller); stack();}profile-1ms/arg1/{ printf("%-24Y %-8d %-16s %-24p %-24p\n", walltimestamp, stackdepth, execname, arg1, caller); ustack();}


Output from Profiler D Script$ sudo ./prof1.d > prof1.out ^Cbash-3.2$ ls -l prof1.out-rw-r--r-- 1 max staff 33694762 Mar 21 11:20 prof1.out

bash-3.2$ less prof1.outTimestamp Depth Process Hot Frame Caller 2014 Mar 21 11:20:04 6 dtrace ffffff80290d41b2 ffffff80291f3ae1

mach_kernel`0xffffff80290d4060+0x152 mach_kernel`VNOP_IOCTL+0x150 mach_kernel`0xffffff80291f39b0+0x131 mach_kernel`fo_ioctl+0x43 mach_kernel`ioctl+0x466 mach_kernel`unix_syscall64+0x1f3 mach_kernel`hndl_unix_scall64+0x162014 Mar 21 11:20:04 1 kernel_task ffffff80290dd76e 0

mach_kernel`machine_idle+0x1de mach_kernel`call_continuation+0x17...


DTrace Scripts Availableon OS X

$ man -k dtracebitesize.d(1m) - analyse disk I/O size by process. Uses DTracecpuwalk.d(1m) - Measure which CPUs a process runs on. Uses DTracecreatbyproc.d(1m) - snoop creat()s by process name. Uses DTracedappprof(1m) - profile user and lib function usage. Uses DTracedapptrace(1m) - trace user and library function usage. Uses DTracediskhits(1m) - disk access by file offset. Uses DTracedispqlen.d(1m) - dispatcher queue length by CPU. Uses DTracedtrace(1) - generic front-end to the DTrace facilitydtruss(1m) - process syscall details. Uses DTraceerrinfo(1m) - print errno for syscall fails. Uses DTraceexecsnoop(1m) - snoop new process execution. Uses DTracefddist(1m) - file descriptor usage distributions. Uses DTracefilebyproc.d(1m) - snoop opens by process name. Uses DTracehotspot.d(1m) - print disk event by location. Uses DTrace...

•42 scripts available, and more can be found at http://www.dtracebook.com/index.php/Main_Page


Example - dtruss• Trace system calls

$ sudo dtruss -n Mail PID/THRD SYSCALL(args) = return 3113/0x47af: select(0x60, 0x61000020C600, 0x61000020C680, 0x0, 0x0) = 1 0 3113/0x47af: recvfrom(0x22, 0x1132ADAA0, 0x100) = 1 0 3113/0x1a3059: kevent64(0x3, 0x11623DE18, 0x1) = 1 0 3113/0x46b0: workq_kernreturn(0x20, 0x0, 0x1) = 0 0 3113/0x46b0: kevent64(0x3, 0x0, 0x0) = 1 0 3113/0x179187: fcntl(0x8, 0x8, 0x117BB8900) = 0 0 3113/0x179187: fcntl(0x8, 0x8, 0x117BB8920) = 0 0 3113/0x179187: fcntl(0x8, 0x8, 0x117BB8A60) = 0 0 3113/0x179187: pread(0x6, "\r\0", 0x1000, 0xC8C0000) = 4096 0 3113/0x179187: workq_kernreturn(0x20, 0x0, 0x1) = 0 0 3113/0x179187: pwrite(0x7, "\0", 0x1018, 0x3DFC90) = 4120 0 3113/0x179187: pwrite(0x7, "\0", 0x1018, 0x3E0CA8) = 4120 0 3113/0x1a28d7: open("/Users/max/Library/Mail/V2/[email protected]@imap.gmail.com/[Gmail].mbox/All Mail.mbox/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX/Data/8/7/1/Messages/178177.emlx\0", 0x8000, 0x0) = 46 0...


mailto:[email protected]


Example - iosnoop• Trace Disk I/O Events

$ sudo iosnoop -aSTRTIME DEVICE MAJ MIN UID PID D BLOCK SIZE PATHNAME ARGS2014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132761912 4096 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132761952 16384 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132761976 4096 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132762576 16384 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132762840 4096 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132763224 16384 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132763320 8192 ??/Messages/177915.emlx.tmp Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132764944 4096 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132765360 16384 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132765472 12288 ??/Messages/177917.emlx.tmp Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132767000 8192 ??/Messages/177918.emlx Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132767152 16384 ??/Messages/177924.emlx.tmp Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132762608 12288 ??/Messages/177913.emlx Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132764920 16384 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132767016 8192 ??/Messages/177919.emlx.tmp Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132762896 12288 ??/Messages/177914.emlx Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132765384 4096 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 502 3113 W 132766960 20480 ??/MailData/Envelope Index-wal Mail\02014 Mar 21 15:33:00 ?? 1 2 0 128 R 24160560 4096 ??/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX/reverseDirectoryStore mds_stores\0...


Example - opensnoop• Trace open(2) calls on files

$ sudo opensnoop -aTIME STRTIME UID PID FD ERR PATH ARGS276685505483 2014 Mar 21 15:39:59 0 128 5 0 . mds_stores\0276685505676 2014 Mar 21 15:39:59 0 128 5 0 . mds_stores\0276688258585 2014 Mar 21 15:40:02 502 17327 10 0 /Users/max/Library/Saved Application State/org.gnu.Aquamacs.savedState/data.data Aquamacs\0276688258829 2014 Mar 21 15:40:02 502 17327 10 0 /Users/max/Library/Saved Application State/org.gnu.Aquamacs.savedState/windows.plist Aquamacs\0276688259202 2014 Mar 21 15:40:02 502 17327 10 0 /Users/max/Library/Saved ...


Example - hfsslower• Trace slow reads/writes on hfs File System (from DTrace book)

$ sudo ./dtbook_scripts/Chap5/hfsslower.d -x dynvarsize=25m 1TIME PROCESS D KB ms FILE2014 Mar 22 14:09:48 mds W 0 3 journal.12014 Mar 22 14:09:50 mdworker R 0 4 Info.plist/..namedfork/rsrc2014 Mar 22 14:10:42 bash R 0 4 ps/..namedfork/rsrc2014 Mar 22 14:12:50 vmware-vmx W 15 4 Virtual Disk-s001.vmdk2014 Mar 22 14:12:50 vmware-vmx W 1 4 Virtual Disk-s001.vmdk2014 Mar 22 14:12:50 vmware-vmx W 5 4 Virtual Disk-s001.vmdk2014 Mar 22 14:13:19 Mail W 1325 4 156241.emlx.tmp2014 Mar 22 14:13:58 fontd R 0 4 GillSans.ttc/..namedfork/rsrc2014 Mar 22 14:14:09 Mail W 1912 7 156197.emlx.tmp2014 Mar 22 14:14:21 Mail R 1913 2 156197.emlx2014 Mar 22 14:14:21 Keynote W 0 4 data.data2014 Mar 22 14:14:26 AppleSpell R 0 4 findNames/..namedfork/rsrc2014 Mar 22 14:14:34 mdworker R 0 4 Info.plist/..namedfork/rsrc2014 Mar 22 14:14:49 mds W 0 3 journal.12014 Mar 22 14:14:56 Keynote R 256 1 using_dtrace.key


Example - soconnect_mac.d• Trace connect(2) calls (from DTrace book)

$ sudo ./dtbook_scripts/Chap6/soconnect_mac.dPassword:PID PROCESS FAM ADDRESS PORT LAT(us) RESULTdtrace: error on enabled probe ID 2 (ID 1035: syscall::connectx:entry): invalid address (0x0) in action #1 at DIF offset 32166 acwebsecagent 2 XXX.XXX.XXX.XXX 80 41 In progress166 acwebsecagent 2 XXX.XXX.XXX.XXX 80 48 In progressdtrace: error on enabled probe ID 2 (ID 1035: syscall::connectx:entry): invalid address (0x0) in action #1 at DIF offset 32dtrace: error on enabled probe ID 2 (ID 1035: syscall::connectx:entry): invalid address (0x0) in action #1 at DIF offset 32166 acwebsecagent 2 XXX.XXX.XXX.XXX 80 63 In progressdtrace: error on enabled probe ID 2 (ID 1035: syscall::connectx:entry): invalid address (0x0) in action #1 at DIF offset 3...


Example - soconnect_mac.d(Continued)

• What is “dtrace: error on enabled probe ID 2 (ID 1035: syscall::connectx:entry): invalid address (0x0) in action #1 at DIF offset 32” ?

• probe ID 2 is the second probe:

syscall::connect*:entry{ /* assume this is sockaddr_in until we can examine family */ this->s = (struct sockaddr_in *)copyin(arg1, sizeof (struct sockaddr)); this->f = this->s->sin_family;}



• What is arg1 to connectx()?

$ sudo dtrace -n 'syscall::connectx:entry{printf("arg0 = %x arg1 = %x arg2 = %x arg3 = %x arg4 = %x\n", arg0, arg1, arg2, arg3, arg4);}'dtrace: description 'syscall::connectx:entry' matched 1 probeCPU ID FUNCTION:NAME 2 1035 connectx:entry arg0 = 14 arg1 = 0 arg2 = 0 arg3 = 7fc42bd1fd10 arg4 = 10

4 1035 connectx:entry arg0 = 1a arg1 = 0 arg2 = 0 arg3 = 7fc42be471a0 arg4 = 10

0 1035 connectx:entry arg0 = 10 arg1 = 0 arg2 = 0 arg3 = 11b5380e0 arg4 = 10

7 1035 connectx:entry arg0 = 14 arg1 = 0 arg2 = 0 arg3 = 7fc429725bf0 arg4 = 10...



• What is arg3 to connectx()?

• Assume it is a sockaddr_in.#!/usr/sbin/dtrace -qs

inline int af_inet = 2;dtrace:::BEGIN{ printf("%-6s %-16s %-3s %-16s %-5s %8s\n", "PID", "PROCESS", "FAM", "ADDRESS", "PORT", "LAT(us)");}

syscall::connectx:entry{ this->s = (struct sockaddr_in *)copyin(arg3, sizeof (struct sockaddr)); this->f = this->s->sin_family; self->inconnectx = 1;}



syscall::connectx:entry/this->f == af_inet/{ self->family = this->f; self->port = (this->s->sin_port & 0xFF00) >> 8; self->port |= (this->s->sin_port & 0xFF) << 8;

this->a = (uint8_t *)&this->s->sin_addr; this->addr1 = strjoin(lltostr(this->a[0] + 0ULL), strjoin(".", strjoin(lltostr(this->a[1] + 0ULL), "."))); this->addr2 = strjoin(lltostr(this->a[2] + 0ULL), strjoin(".", strjoin(lltostr(this->a[1] + 0ULL), "."))); this->addr2 = strjoin(lltostr(this->a[2] + 0ULL), strjoin(".", lltostr(this->a[3] + 0ULL))); self->address = strjoin(this->addr1, this->addr2); self->start = timestamp;}



syscall::connectx:return/self->start/

{ this->delta = (timestamp - self->start) / 1000; printf("%-6d %-16s %-3d %-16s %-5d %8d\n", pid, execname, self->family, self->address, self->port, this->delta); self->family = 0; self->address = 0; self->port = 0; self->start = 0;}



$ sudo ./connectx.dPID PROCESS FAM ADDRESS PORT LAT(us) 8801 com.apple.WebKi 2 XXX.XXX.XXX.XXX 80 418801 com.apple.WebKi 2 XXX.XXX.XXX.XXX 80 348801 com.apple.WebKi 2 XXX.XXX.XXX.XXX 80 4321473 ocspd 2 XXX.XXX.XXX.XXX 80 978801 com.apple.WebKi 2 XXX.XXX.XXX.XXX 80 41...


Flame Graphs

• Visualization of profiled code paths

• Shows distribution of code paths over time

• https://github.com/brendangregg/FlameGraph/


https://github.com/brendangregg/FlameGraph/


An Example Flame Graph•Colors have no meaning•Left to right is not time sequenced•Moving cursor over item shows function, number of times that function occurs , and percentage.•Longer horizontal bands implies longer time in that function or a function called from that function


Building Flame Graphs Example - DTrace Script

#!/usr/sbin/dtrace -s

#pragma D option quiet

profile:::profile-97hz/arg0 != 0/{

@k[stack()] = count();}

profile:::profile-97hz/arg1 != 0 && execname != "dtrace"/{

@u[ustack()] = count();}

tick-60s {exit(0);}


Building Flame Graphs Example (Continued)

$ git clone https://github.com/brendangregg/FlameGraph/$ sudo ./prof.d -o prof.out$ ls -l prof3.out-rw-r--r-- 1 root staff 2286203 Mar 24 11:35 prof.out$ ./stackcollapse.pl prof.out | ./flamegraph.pl > prof.svg$ open prof3.svg$

•Alternatively$ git clone https://github.com/davepacheco/node-stackvis...$ cd node-stackvis$ make...$ stackvis dtrace flamegraph-svg < prof.out > prof1.svg




https://github.com/davepacheco/node-stackvis

https://github.com/davepacheco/node-stackvis

Node.js - Example

• Node.js (and other higher level languages) has probes built in.

• Some Node.js modules also have DTrace support

• Example is from https://github.com/mcavage/node-restify, (git clone and then npm install)


https://github.com/mcavage/node-restify

https://github.com/mcavage/node-restify

Node.js - Example Continued/* restifyserver.js */var restify = require('restify');

var server = restify.createServer({ name: 'myapp', version: '1.0.0'});server.use(restify.acceptParser(server.acceptable));server.use(restify.queryParser());server.use(restify.bodyParser());

server.get('/echo/:name', function (req, res, next) { res.send(req.params); return next();});

server.listen(8080, function () { console.log('%s listening at %s', server.name, server.url);});


Node.js - Example Continued/* restifyclient.js */var assert = require('assert');var restify = require('restify');

var client = restify.createJsonClient({ url: 'http://localhost:8080', version: '~1.0'});

client.get('/echo/mark', function (err, req, res, obj) { assert.ifError(err); console.log('Server returned: %j', obj);});


http://localhost:8080

http://localhost:8080

Node.js Example - Continued$ node restifyserver.jsmyapp listening at http://0.0.0.0:8080

$ sudo dtrace -q -l -n 'restify*:::{}' ID PROVIDER MODULE FUNCTION NAME214546 restify28832 mod-0x100f00420 route-start route-start214547 restify28832 mod-0x100f00420 handler-start handler-start214548 restify28832 mod-0x100f00420 handler-done handler-done214549 restify28832 mod-0x100f00420 route-done route-done214550 restify28832 mod-0x100f00420 client-request client-request214551 restify28832 mod-0x100f00420 client-response client-response217839 restify28832 mod-0x100f00420 client-error client-error


http://0.0.0.0:8080

http://0.0.0.0:8080

Node.js Example - Continued$ sudo dtrace -l -n 'node*:::{}' ID PROVIDER MODULE FUNCTION NAME214536 node28832 node _ZN4nodeL14dtrace_gc_doneEN2v86GCTypeENS0_15GCCallbackFlagsE [node::dtrace_gc_done(v8::GCType, v8::GCCallbackFlags)] gc-done214537 node28832 node _ZN4nodeL15dtrace_gc_startEN2v86GCTypeENS0_15GCCallbackFlagsE [node::dtrace_gc_start(v8::GCType, v8::GCCallbackFlags)] gc-start214538 node28832 node _ZN4node26DTRACE_HTTP_CLIENT_REQUESTERKN2v89ArgumentsE [node::DTRACE_HTTP_CLIENT_REQUEST(v8::Arguments const&)] http-client-request214539 node28832 node _ZN4node27DTRACE_HTTP_CLIENT_RESPONSEERKN2v89ArgumentsE [node::DTRACE_HTTP_CLIENT_RESPONSE(v8::Arguments const&)] http-client-response214540 node28832 node _ZN4node26DTRACE_HTTP_SERVER_REQUESTERKN2v89ArgumentsE [node::DTRACE_HTTP_SERVER_REQUEST(v8::Arguments const&)] http-server-request...


Node.js Example - Continued$ node ./restifyclient.js Server returned: {"name":"mark"}$ sudo dtrace -qn 'restify*:::{printf("%s: %s:

%s\n", probeprov, probefunc, probename);}'restify28832: route-start: route-startrestify28832: handler-start: handler-startrestify28832: handler-done: handler-donerestify28832: handler-start: handler-startrestify28832: handler-done: handler-donerestify28832: handler-start: handler-startrestify28832: handler-done: handler-donerestify28832: handler-start: handler-startrestify28832: handler-done: handler-donerestify28832: handler-start: handler-startrestify28832: handler-done: handler-donerestify28832: route-done: route-donerestify28844: client-response: client-responserestify28844: client-request: client-request


What’s Missing?

• ustack helpers - Allows jstack() action (stack backtrace showing function calls in higher level languages)

• CPU performance counters?

• Some source


References

• http://www.dtrace.org

• http://dtrace.org/blogs/dap/category/nodejs/

• http://dtrace.org/blogs/brendan/2011/10/10/top-10-dtrace-scripts-for-mac-os-x/

@mrbruning, [email protected]


http://www.dtrace.org

http://www.dtrace.org

http://dtrace.org/blogs/dap/category/nodejs/








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