Is your profiler speaking the same language as you? -- Docklands JUG

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Is your profiler speaking the
same language as you?
Simon Maple
@sjmaple

@sjmapleSimon Maple -

Agenda
• Performance Tools
• Performance by numbers
• Sampling vs Tracing
• XRebel
• JRebel
3

Performance Tools
• Java Monitoring Tools
• Java Profilers
• Java Testing Tools
5

Performance report
6

RebelLabs reports
7

The Journey of Performance
16

https://twitter.com/shipilev/status/578193813946134529

A
B
C
D E
Performance
Code complexity

Improving
Optimizing
Last 5%
Last 1%
A
B
C
D E

Profiling
CPU
Tracing Sampling
Memory
Usage Allocation
We are only talking about this part today

JVM has ability to produce thread dump:
Press Ctrl+Break on Windows
kill -3 PID on *nix
"http-nio-8080-exec-1"#40 daemon p...

Sampling interval : 20 ms
Sample count: 4

Sampling interval : 1 ms
Sample count: 100+

Sampling
main()
foo()
bar()
baz()
never captured :(

Safepoint bias
Safepoints
main()
foo()
bar()
baz()

Safepoint bias
Safepoints
main()
foo()
bar()
baz()

Taming safepoint bias
Java Mission Control
Proprietary protocol
Java 7u40
Honest Profiler
https://github.com/RichardWarbur...

public
void
businessMethod()
{ 

long
start
=
System.currentTimeMillis(); 

work(); 

...

Tracing
public
void
businessMethod()
{ 

long
start
=
System.nanoTime(); 

work(); 

...

Tracing
public
void
businessMethod()
{ 

Profiler.start(“businessMethod");

try
{ 

...

System.nanoTime
System.currentTimeMillis
Parallel thread updating easily accessible
memory location
sleep-wakeup-update
yi...

class
Profiler
{

 

Loop
loop; 
 

public
static
void
start(String
method)
{ 

...

public
class
Loop
implements
Runnable
{ 

private
volatile
long
time; 

...

Nano seconds put into perspective
Reading memory is not free.
It takes cycles = nanoseconds
Each (software) layer is not f...

Nano seconds put into perspective
http://shipilev.net/blog/2014/nanotrusting-nanotime/
Nanotrusting the NanoTime
granulari...

Sleep timer: time-slicing & scheduling
Minimum sleep times:
Win8: 1.7 ms (1.0 ms using JNI + socket poll)
Linux: 0.1 ms
OS...

public
class
Loop
implements
Runnable
{ 

private
volatile
long
time; 

...

public
class
Loop
implements
Runnable
{ 

private
volatile
long
time; 

...

Busy Loop
public
class
Loop
implements
Runnable
{ 

private
volatile
long
time; 

...

public
class
Loop
implements
Runnable
{ 

private
volatile
long
time; 

...

main()
foo()
bar()
baz()
Tracing
relatively higher overhead for fast methods :(

Database access
Web Services
RMI
Various application layers
3rd-party components
HTTP session
Exceptions
Caches
File syste...

Questions you should be asking
……..
……..
……..
……..

Questions you should be asking
Where was most of the time spent?
How many SQL queries were executed?
How much time did the...

Most improvement gained here!
This is where we should focus first!
A
B
C
D E

Download trials and get FREE
shirts :)
JRebel: http://0t.ee/docklandsjr
XRebel: http://0t.ee/docklandsxr
47

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