1 grid applications control based on synchronizers, d. kopanski , j. borkowski , m. tudruj the...

1GRID applications control based on synchronizers, D. Kopanski*, J. Borkowski*, M. Tudruj

The Cracow Grid Workshop 2004

D. Kopanski*, J. Borkowski*, M. Tudruj* x

*Polish-Japanese Institute of Information Technology, 86 Koszykowa Str., 02-008 Warsaw, Poland

xInstitute of Computer Science, Polish Academy of Sciences21 Ordona Str. 01-237 Warsaw, Poland

{janb, damian, tudruj}@pjwstk.edu.pl

GRID applications control based on synchronizers



Introduction

The principles of application control

Implementation issues

Conclusions

Contents



•Monitoring global states

•Strongly Consistent Global States (SCGS)

•Observed Global States (OGS)

•Activation and cancellation

•P-GRADE system

•PS-GRADE system

Introduction



Arrows represent reliable, asynchronous communication channels

P1

P2 P3 P4

S a

state information

S b

control

Processes can communicate with a number of Synchronizers. Synchronizers learn state information from processes and send back control information.

synchronizers

processes

Monitoring global states



•There is no global clock, no shared memory

•Synchronizer must be able to order properly incoming events to build Strongly Consistent Global States (SCGS)

•SCGS is a combination of process local states, one state from each process, such that the local states are pairwise concurrent. E.g. <s1,t1> is a SCGS, <s1,t2> is not.

P1

P2

sync

e1 e2

f1 f2

s1

t2t1

m1m2

Monitoring consistent global states



•Events must have timestamps to be able to order messages correctly. Logical vector clocks or real time intervals based on roughly synchronized local clocks can be used

•If process local clocks are synchronized with a known accuracy, then real time interval timestamps can be used to identify SCGS

process 1

process 2

e1 e2 e3 e4 e5

e1 e3 e2 e4

SCGS duration period e1 event occurrence interval, an event occurred somewhen within this time interval

S1 S2 S3

S1 a SCGS on a linear lattice

Strongly Consistent Global States



Observed states

P1

P2

sync

e1 e2

f1 f2

-f1

e1f1

e1f2

e2f2

•We don’t need a clock synchronization•We don’t need QoS (Quality Of Service) •The reaction is fired immediately



computations

activated procedure

continued computations

activity

cancellation handling

cancelled fragment

control signal

control signal

another activity

spared time

Computation activation and cancellation caused by predicate evaluation



A complete graphical programming environment for developing message passing applications designed at Parallel and Distributed Systems Laboratory of the SZTAKI Institute of Hungarian Academy of

Sciences

•Application level specifies processes

and their interconnections

•Process level defines control flow diagram of a process

•Text level is used to enter sequential C code into elements of a flow diagram

loopbegin

receivefrom port 0

send throughport 1

sequential code in C

GRADE system



standard message passing channels

local state info transfer channels

signal transfer channels

GRADE extension – state information acquisition



Start

Wait for a process/application state information message

Is a new SCGS / OGS detected?

Predicate 1 satisfied?

...

Update state records and make them available for

control predicates

Send sync signals

Yes

Predicate 2 satisfied?

Predicate k satisfied?

Send sync signals

Send sync signals

Yes Yes Yes

No

State messages

No No No

Condition 2 Condition k Condition 1

GRADE extension - synchronizer



GRADE extension – synchronizerCondition Window



condition

send signal

reception of state variables

GRADE extension – synchronizercontrol flow window



Start signal-sensitive region "watching-

signal"

End signal-sensitive region "endwatching-

signal"

Resume interrupted

computations

Cancel computations

Send state

End signal- insensitive region

Start signal- insensitive region

GRADE extension – Process - control flow window



GRADE extension – synchronizer hierarchy



The principles of application control

Control of GRID application by:•Data control flow (similarly to P-GRADE Workflow implemented by SZTAKI) , based on input and output files for cluster application •GRID Synchronizer :

•Collects information (vector of state) about application state•Detects SCGS or OGS •Computes conditions •Sends signals to the application



A GRID-level synchronizer inserted into a workflow graph A1

1

A2 A3

1 1

A4

1

4 4 5 5

A5

1 2

Synch1

2 1 2 2

3 3 4 3

5 6

2 3

A6

3 4

1



A GRID-level synchronizer and an application (example)

GRID Synchronizer

Application A2

Application A3

Application A4

Application A5



Implementation concepts

Hosting environment

Web Service Engine

Grid Service Container

User Defined Service

Base Service

System Level Service

OGSI Spec Implementation Security Infrastructure

GGWS GGMS

GT3 core architecture and PS-GRADE service

•We use the Globus Toolkit v3 (GT3) to implement web service infrastructure •User Defined Service layer will be used for signal and message delivery = Grade-Globus-Web-Service (GGWS) and for the application maintenance service on the GRID= Grade-Globus-Maintenance-Service (GGMS)•Inter-grid communication

with SOAP protocol •We also use :

•GridFTP services for input, output files and program code transfer•GRAM serviced for local job managment



Grade-Globus-Maintenance-Service

GGMS will be the central maintenance service of GRID-Grade application.Main function of GGMS :•Checks the start conditions for applications and if they are true, initiates execution of application•Makes the ”GRID execution map” with information about current running applications and sends it to the GGSW (if GGSW need it)•Makes the global (model) clock available to all GGSW•GGCSW use :

•GridFTP services for input, output files and program code transfer•GRAM services for job managment •SOAP for communication with GGSW



GGMS – model of execution •Start = execute GGCSW on selected GLOBUS Server•LOAD Data = All executions, input files , execution Map to the selected GLOBUS Server with the use of GridFTP•Starts the Global Synchronizers•Main LOOP - Until all applications complete

•Checks all starting conditions•If any fulfilled then

•Run the ready Grid applications •Updates the GRID execution map•Sends the execution map to the GGSW (if GGSW need it)

•Checks the state of all running application •If any application completes then

•Gets the output files •Updates the GRID execution map•Sends the execution map to the GGSW

•Maintains the time synchronisation of all running GGSW•Stops the Global Synchronizers •Waits for output data request



GGMS – an application starting pattern •Makes a new instance of GGSW on selected GLOBUS server

•Sends the execution file and input file to the GLOBUS server throught GridFtp service

•Executes program by the use of the relevant GRAM service in interactive mode or in the batch mode

•Creates then communication interface between the GGSW and the started application



Globus Resource Allocation Manager – GRAM service •GRAM simplifies the use of remote systems by providing a single standard interface for requesting and using remote system resources for the execution of jobs. •The most common use of GRAM is remote job submission and control. •Grid Service Factory Pattern

•Create Service •Service instance is created •The request is validated •User’s job request is *ready* to be started

•Start operation •User’s job request is started •Service instance monitors job request •Updates request SDE (Service Data Element)

•Job control •Ensures client received a handle to the job before resources have been consumed

GGMS

GRAM

Local managment Machanism

PS-GRADE Application

GGMS and GRAM



The clock synchronisation

•If an application uses the Strongly Consistent Global States we have to implement a clock synchronisation mechanism

•We will use the GGMS’s clock as a reference clock

•After clock synchronisation call, all the GGWSs measure the difference between their local clocks and the referenced clock

•When the local synchronizer sends a state message to the global synchronizer, GGWS does the timestamp correction by adding to the timestamp the value of time difference versus the reference clock.



Grade-Globus-Web-Service (GGWS)•Main functions of GGSW

•Implements communication between local synchronizers and the global synchronizer (with SOAP Messaging)

•Corrects timestamps attached to state messages(in the SCGS mode)

•Maintains the GRID CENTER time-synchronisation process

•Monitors running application



Inter GRID Communication concepts



The paper has presented how the synchronization-based parallel application control can be extended and ported onto the GRID level. With the use of the proposed method we can create an advanced control of many applications running in the GRID environment. Inter–application coordination between programs, which are executed on different GRID sites, is supported.

We have employed the Globus Toolkit as the required middleware implementation platform.

Full implementation of the described extension of the PS-GRADE system will be done in co-operation with P-GRADE authors i.e. SZTAKI Institute of Hungarian Academy of Sciences

Conclusions

1 grid applications control based on synchronizers, d. kopanski , j. borkowski , m. tudruj the...

Documents

grid applications control

cracow grid workshop

control information

synchronizers processes

control flow diagram

data control flow

number of synchronizers

monitoring global states

1 grid applications control based on synchronizers, d. kopanski *, j. borkowski *, m. tudruj the...

1 grid applications control based on synchronizers, d. kopanski , j. borkowski , m. tudruj the...