1. Gearman
From the Worker's Perspective

2. /usr/bin/whoami
• Brian Aker
• HP Fellow
• Previously MySQL, Slashdot, Sun Microsystems

3. What is Gearman?

4. “The way I like to think of Gearman is a
massively distributed fork mechanism”
-Joe Stump, Digg
“The Not Mechanical Turk”
-Don MacAskill, SmugMug

6. resize_image()
do {
(“resize_image”) …
return $image;
}

7. (Livejournal)

13. Server
Provides Asynchronous and Synchronous Requests
Restarts Work
Durable Requests (MySQL, Postgres,...)
Gearman Protocol/HTTP
Epoch Scheduling
Logging
(also available, native Servers in Java, Erlang, and Perl)

14. Client
# Create our client object.$gmclient= new
GearmanClient();# Add default server
(localhost).$gmclient->addServer();
$result= $gmclient->do("reverse", "Hello!");
echo "Success: $resultn";

15. Worker
# Create our worker object.$gmw= new
GearmanWorker();# Add default server
(localhost).$gmw->addServer();
$gmw->addFunction("reverse",
"reverse_fn");while ($gmworker->work())
{…}

16. Worker Function
function reverse_fn($job){ $workload= $job-
>workload(); $result= strrev($workload);
return $result;}

17. Lots of functions...
$gmw->addFunction("resize", "resize_fn");
$gmw->addFunction("grep", "grep_fn");
$gmw->addFunction("fetch_url", "fetch_url");

18. Function
gearman_return_t fetch_url(gearman_job_st *job, void*){ const char *workload=
gearman_job_workload(job); size_t workload_size=
gearman_job_workload_size(job);
gearman_job_send_status(job, 0, 100);
…
gearman_job_send_data(job, chunk, sizeofchunk);
…
gearman_job_send_status(job, 50,100);
… if (issue_warning)
gearman_job_warning(job, “I'm sorry, Dave. I'm afraid I can't do that.”, size);
return GEARMAN_SUCCESS;}

19. Worker Return
GEARMAN_SUCCESS
GEARMAN_FATAL
GEARMAN_ERROR
GEARMAN_SHUTDOWN

20. Your Client
request()
Client API
(C, PHP, Perl, Python, Java,Drizzle, ...)
Network,
Highly Available, Server
Fault Tolerant
Worker API
(C, PHP, Perl, Python, Java, ...)
Your Worker
function()

21. Your Client
resize_image(“ request()
…”);
Client API
(C, PHP, Perl, Python, Java,Drizzle, ...)
Network,
Highly Available, Provided by
Server
Fault Tolerant Gearman
Worker API
resize_image() (C, PHP, Perl, Python, Java, ...)
{
…;
return resized; Your Worker
} function()

22. CPU? event()

24. multiple languages

25. Connectors?
• C/C++
• PHP
• Python
• Java
• MySQL and Postgres
• ....

26. Other items of
interest?
• Work status requests.
• Chunked Data.
• Exception Handling.
• Up to 4gig message sizes.
• Threaded server.
• Coalescence (the stealth killer feature)

27. Namespaces
Foo::resize_image() Acme::resize_image()
{ {
… …
return $image; return $image;
} }

28. Better Map Reduce?

29. reduce()
{…}
map(list[…],
map()
reduce());
{…}
reduce()
{…}
reduce()
{…}

30. Map @#$@# ?

31. find()
Partitioning
find()
{A...K}
{L...Q}
{R...Z} find()

32. Partitioning
gearman_return_t split_worker(gearman_job_st *job, void* /* context */){ const
char *workload= gearman_job_workload(job); size_t workload_size=
gearman_job_workload_size(job); const char *chunk_begin= workload; for
(size_t x= 0; x < workload_size; x++) { if (workload[x] == 0 or workload[x] ==
' ') { gearman_job_send_data(job, chunk_begin,
workload +x -chunk_begin); chunk_begin=
workload +x +1; } } return GEARMAN_SUCCESS;}

33. $resu
Aggregation lt
$resu
lt
+ result
+ result
+ result $resu
lt
= sum result

34. Aggregation
gearman_return_t cat_aggregator (gearman_aggregator_st *,
gearman_task_st *task,
gearman_result_st *result){ std::string
string_value; do { gearman_result_st *result_ptr=
gearman_task_result(task);
string_value.append(gearman_result_value(result_ptr),
gearman_result_size(result_ptr));
} while ((task= gearman_next(task)));
gearman_result_store_value(result, string_value.c_str(),
string_value.size()); return
GEARMAN_SUCCESS;}

35. Do we have to
partition?
(What other tricks exist!)

36. Pipeline
Store() Resize() Publish()

37. Future
0.32 Released
Custom Logging Plugins
Client/Worker Configuration
Extended Administrative Commands
SSL
Status lookup via Unique Identifier
Job Result Cache
Uplift!

38. Gearman.inf
o
• Gearman.org (...)
• http://launchpad.net/gearmand/
• twitter: brianaker
• blog: blog.krow.net