[jira] Assigned: (TUSCANY-2170) Synchronizing the access to SCADefinitions
[ https://issues.apache.org/jira/browse/TUSCANY-2170?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Venkatakrishnan reassigned TUSCANY-2170: Assignee: Venkatakrishnan Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Assignee: Venkatakrishnan Priority: Minor Fix For: Java-SCA-Next Attachments: SCADefinitionsImpl-JIRA-2170.patch http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
[jira] Resolved: (TUSCANY-2170) Synchronizing the access to SCADefinitions
[ https://issues.apache.org/jira/browse/TUSCANY-2170?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Venkatakrishnan resolved TUSCANY-2170. -- Resolution: Fixed Patch applied in r646208. Thanks for the patch. Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Assignee: Venkatakrishnan Priority: Minor Fix For: Java-SCA-Next Attachments: SCADefinitionsImpl-JIRA-2170.patch http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
[jira] Updated: (TUSCANY-2170) Synchronizing the access to SCADefinitions
[ https://issues.apache.org/jira/browse/TUSCANY-2170?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Ramkumar Ramalingam updated TUSCANY-2170: - Attachment: SCADefinitionsImpl-JIRA-2170.patch Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Priority: Minor Fix For: Java-SCA-Next Attachments: SCADefinitionsImpl-JIRA-2170.patch http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronizing the access to SCADefinitions
Ramkumar, Sorry for the delay in responding. I think you are probably right that CopyOnWriteArrayList is the way to go. Presumably there will be far more contributions traversing the definitions (looking for policy sets etc) than contributions adding to the contributions. So trading off a high penalty on write for no penalty on traversal sounds like a good idea. The write penalty could be mitigated by batching updates; i.e. instead of adding new intents, policy sets, etc. to the lists one-by-one, collect them and make one update to each list. Greg Dritschler On Wed, Apr 2, 2008 at 5:56 AM, Ramkumar R [EMAIL PROTECTED] wrote: Hi All, I am new to Tuscany Community, being interested in contributing and trying to catch up. Right now am going through the code to get a feel of it and the threading issue (as mentioned in http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html) seems to be something simple that I can fix to try a hand with Tuscany. Looking at the current implementation SCADefinitionsImpl.java uses java ArrayList to store the list of policy sets, intents, binding types etc. Possible solutions to this issue woule be to a) synchronize the methods that does the operations like clear/addAll OR b) replace the existing ArrayList with Vectors OR c) replace the existing ArrayList with CopyOnWriteArrayList (new with Java1.5) Option (a) seems to be a bad idea for me as it would lock the entire method, instead i would go for option (b) OR (c). Going for option (b), using Vectors OR Collections.synchronizedList synchronizes your list object. However, the iterators implemented in the java.util Collections classes are fail-fast, which means that if one thread changes a collection while another thread is traversing it through an Iterator, the next Iterator.hasNext() or Iterator.next() call will throw ConcurrentModificationException. If we have to prevent ConcurrentModificationException, we must lock the entire List while you are iterating by wrapping it with a synchronized block, which inturn is costly. Option (c) seems to be a good solution to the above problem, the CopyOnWriteArrayList class from util.concurrent (which will also appear in the java.util.concurrent package in JDK 1.5) is a thread-safe implementation of ArrayList that offers far better concurrency. Multiple reads can almost always execute concurrently, simultaneous reads and writes can usually execute concurrently, and multiple simultaneous writes can often execute concurrently. Also CopyOnWriteArrayList contains a mutable reference to an immutable array, so as long as that reference is held fixed, you get all the thread-safety benefits of immutability without the need for locking. I have opened a JIRA (Tuscany-2170) to fix this issue. Please suggest me if this one is the right approach. -- Thanks Regards, Ramkumar Ramalingam
Re: Synchronizing the access to SCADefinitions
Oops, meant to say ...than contributions adding definitions. On Fri, Apr 4, 2008 at 4:00 PM, Greg Dritschler [EMAIL PROTECTED] wrote: Ramkumar, Sorry for the delay in responding. I think you are probably right that CopyOnWriteArrayList is the way to go. Presumably there will be far more contributions traversing the definitions (looking for policy sets etc) than contributions adding to the contributions. So trading off a high penalty on write for no penalty on traversal sounds like a good idea. The write penalty could be mitigated by batching updates; i.e. instead of adding new intents, policy sets, etc. to the lists one-by-one, collect them and make one update to each list. Greg Dritschler On Wed, Apr 2, 2008 at 5:56 AM, Ramkumar R [EMAIL PROTECTED] wrote: Hi All, I am new to Tuscany Community, being interested in contributing and trying to catch up. Right now am going through the code to get a feel of it and the threading issue (as mentioned in http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html) seems to be something simple that I can fix to try a hand with Tuscany. Looking at the current implementation SCADefinitionsImpl.java uses java ArrayList to store the list of policy sets, intents, binding types etc. Possible solutions to this issue woule be to a) synchronize the methods that does the operations like clear/addAll OR b) replace the existing ArrayList with Vectors OR c) replace the existing ArrayList with CopyOnWriteArrayList (new with Java1.5) Option (a) seems to be a bad idea for me as it would lock the entire method, instead i would go for option (b) OR (c). Going for option (b), using Vectors OR Collections.synchronizedList synchronizes your list object. However, the iterators implemented in the java.util Collections classes are fail-fast, which means that if one thread changes a collection while another thread is traversing it through an Iterator, the next Iterator.hasNext() or Iterator.next() call will throw ConcurrentModificationException. If we have to prevent ConcurrentModificationException, we must lock the entire List while you are iterating by wrapping it with a synchronized block, which inturn is costly. Option (c) seems to be a good solution to the above problem, the CopyOnWriteArrayList class from util.concurrent (which will also appear in the java.util.concurrent package in JDK 1.5) is a thread-safe implementation of ArrayList that offers far better concurrency. Multiple reads can almost always execute concurrently, simultaneous reads and writes can usually execute concurrently, and multiple simultaneous writes can often execute concurrently. Also CopyOnWriteArrayList contains a mutable reference to an immutable array, so as long as that reference is held fixed, you get all the thread-safety benefits of immutability without the need for locking. I have opened a JIRA (Tuscany-2170) to fix this issue. Please suggest me if this one is the right approach. -- Thanks Regards, Ramkumar Ramalingam
Synchronizing the access to SCADefinitions
Hi All, I am new to Tuscany Community, being interested in contributing and trying to catch up. Right now am going through the code to get a feel of it and the threading issue (as mentioned in http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html) seems to be something simple that I can fix to try a hand with Tuscany. Looking at the current implementation SCADefinitionsImpl.java uses java ArrayList to store the list of policy sets, intents, binding types etc. Possible solutions to this issue woule be to a) synchronize the methods that does the operations like clear/addAll OR b) replace the existing ArrayList with Vectors OR c) replace the existing ArrayList with CopyOnWriteArrayList (new with Java1.5) Option (a) seems to be a bad idea for me as it would lock the entire method, instead i would go for option (b) OR (c). Going for option (b), using Vectors OR Collections.synchronizedList synchronizes your list object. However, the iterators implemented in the java.util Collections classes are fail-fast, which means that if one thread changes a collection while another thread is traversing it through an Iterator, the next Iterator.hasNext() or Iterator.next() call will throw ConcurrentModificationException. If we have to prevent ConcurrentModificationException, we must lock the entire List while you are iterating by wrapping it with a synchronized block, which inturn is costly. Option (c) seems to be a good solution to the above problem, the CopyOnWriteArrayList class from util.concurrent (which will also appear in the java.util.concurrent package in JDK 1.5) is a thread-safe implementation of ArrayList that offers far better concurrency. Multiple reads can almost always execute concurrently, simultaneous reads and writes can usually execute concurrently, and multiple simultaneous writes can often execute concurrently. Also CopyOnWriteArrayList contains a mutable reference to an immutable array, so as long as that reference is held fixed, you get all the thread-safety benefits of immutability without the need for locking. I have opened a JIRA (Tuscany-2170) to fix this issue. Please suggest me if this one is the right approach. -- Thanks Regards, Ramkumar Ramalingam
[jira] Commented: (TUSCANY-2170) Synchronizing the access to SCADefinitions
[ https://issues.apache.org/jira/browse/TUSCANY-2170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12584098#action_12584098 ] Ramkumar Ramalingam commented on TUSCANY-2170: -- Learnt that using Vectors OR Collections.synchronizedList synchronizes your list object. However, the iterators implemented in the java.util Collections classes are fail-fast, which means that if one thread changes a collection while another thread is traversing it through an Iterator, the next Iterator.hasNext() or Iterator.next() call will throw ConcurrentModificationException. If we have to prevent ConcurrentModificationException, we must lock the entire List while you are iterating by wrapping it with a synchronized block, which inturn is costly. As a solution to the above problem, the CopyOnWriteArrayList class from util.concurrent (which will also appear in the java.util.concurrent package in JDK 1.5) is a thread-safe implementation of ArrayList that offers far better concurrency. Multiple reads can almost always execute concurrently, simultaneous reads and writes can usually execute concurrently, and multiple simultaneous writes can often execute concurrently. Also CopyOnWriteArrayList contains a mutable reference to an immutable array, so as long as that reference is held fixed, you get all the thread-safety benefits of immutability without the need for locking. Hence i believe the best solution would be to go with CopyOnWriteArrayList instead of the current ArrayList used to store the list of policy sets, intents, binding types etc. Please suggest me if this one is the right approach. Thanks. Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Priority: Minor Fix For: Java-SCA-Next http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
[jira] Created: (TUSCANY-2170) Synchronizing the access to SCADefinitions
Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Priority: Minor Fix For: Java-SCA-Next http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
[jira] Commented: (TUSCANY-2170) Synchronizing the access to SCADefinitions
[ https://issues.apache.org/jira/browse/TUSCANY-2170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12583638#action_12583638 ] Ramkumar Ramalingam commented on TUSCANY-2170: -- The current implementation SCADefinitionsImpl.java uses java ArrayList to store the list of policy sets, intents, binding types etc. I believe Instead of synchronizing the methods that does the operations like clear/addAll. I believe the best solution would be to replace the ArrayList with a Vector. Please suggest me if this one is the right approach. Thanks. Synchronizing the access to SCADefinitions -- Key: TUSCANY-2170 URL: https://issues.apache.org/jira/browse/TUSCANY-2170 Project: Tuscany Issue Type: Bug Components: Java SCA Core Runtime Affects Versions: Java-SCA-Next Environment: SVN revision 642920 - Windows Reporter: Ramkumar Ramalingam Priority: Minor Fix For: Java-SCA-Next http://www.mail-archive.com/tuscany-dev%40ws.apache.org/msg29138.html -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
