I'm having a stale attribute with the http session within Websphere 6 and may be related to in memory session replication..
Steps:
Object A.0 - Placed into the session with ID "ABC"
Remove A.0 from the session..
Object A.1 (New instance) - placed into Session with ID "ABC"
retrieve object with ID "ABC" from the session - RESULT: A.1 (Correct)
carry out a Servlet forward or a redirect (issues seen on both functions)..
retrieve "ABC" from the session - RESULT: A.0, the object that was removed from the session..
Notes -
Same Session object (hashcode/session ID) used in steps 1-5 using in
memory replication across 2 JVMs (single cluster)
time duration between steps 2 & 5 is total of 4 seconds
No other external threads have accessed the session in the interim..
Only noticed for 1 specific use-case; haven't encountered this in
other use-cases..
Anyone seen anything like this before where a stale data is being returned from the websphere application server?
Thanks,
Ian.
Are you explicitly writing the changed object back to the session before you forward/redirect? In at least some versions of WebSphere, in some configurations, you must do this to ensure the change is "committed".
(If I find a clear reference for this, I'll update my answer.)
Related
Im running a spring boot application using infinispan 10.1.8 in a 2 node cluster. The 2 nodes are communicating via jgroups TCP. I configured several REPL_ASYNC.
The problem:
One of these caches, at some point is causing the two nodes to exchange the same message over and over, causing high CPU and memory usage. The only way to stop this is to stop one of the two nodes.
More details, here is the configuration.
org.infinispan.configuration.cache.Configuration replAsyncNoExpirationConfiguration = new ConfigurationBuilder()
.clustering()
.cacheMode(CacheMode.REPL_ASYNC)
.transaction()
.lockingMode(LockingMode.OPTIMISTIC)
.transactionMode(TransactionMode.NON_TRANSACTIONAL)
.statistics().enabled(cacheInfo.isStatsEnabled())
.locking()
.concurrencyLevel(32)
.lockAcquisitionTimeout(15, TimeUnit.SECONDS)
.isolationLevel(IsolationLevel.READ_COMMITTED)
.expiration()
.lifespan(-1) //entries do not expire
.maxIdle(-1) // even when they are idle for some time
.wakeUpInterval(-1) // disable the periodic eviction process
.build();
One of these caches (named formConfig) is causing me abnormal communication between the two nodes, this is what happens:
with jmeter I generate traffic load targeting only node 1
for some time node 2 receives cache entries from node 1 via SingleRpcCommand, no anomalies, even formConfig cache behaves properly
after some time a new cache entry is sent to the formConfig cache
At this point the same message seems to keep bouncing between the two nodes:
node 1 sends entry mn-node1.company.acme-develop sending command to all: SingleRpcCommand{cacheName='formConfig', command=PutKeyValueCommand{key=SimpleKey [form_config,MECHANICAL,DESIGN,et,7850]
node 2 receives the entry mn-node2.company.acme-develop received command from mn-node1.company.acme-develop: SingleRpcCommand{cacheName='formConfig', command=PutKeyValueCommand{key=SimpleKey [form_config,MECHANICAL,DESIGN,et,7850]
node 2 sends the entry back to node 1 mn-node2.company.acme-develop sending command to all: SingleRpcCommand{cacheName='formConfig', command=PutKeyValueCommand{key=SimpleKey [form_config,MECHANICAL,DESIGN,et,7850]
node 1 receives the entry mn-node1.company.acme-develop received command from mn-node2.company.acme-develop: SingleRpcCommand{cacheName='formConfig', command=PutKeyValueCommand{key=SimpleKey [form_config,MECHANICAL,DESIGN,et,7850],
node 1 sends the entry to node 2 and so on and on...
Some other things:
the system is not under load, jmeter is running only few users in parallel
Even stopping jmeter this loop doesn't stop
formConfig is the only cache that behaves this way. All the other REPL_ASYNC caches work properly. I deactivated only formConfig cache and the system is working correctly.
I cannot reproduce the problem with two nodes running on my machine
Here's a more complete log file including logs from both nodes.
Other infos:
opendjdk 11 hot spot
spring boot 2.2.7
infinispan spring boot starter 2.2.4
using JbossUserMarshaller
I'm suspecting
something related to transactional configuration
or something related to serialization/deserialization of the cached object
The only scenario where this can happen is when the SimpleKey has different hashCode().
Are there any exceptions in the log? Are you able to check if the hashCode() is the same after serialization & deserialization of the key?
I am trying to understand Laravels session handler and can't find anything online. At the moment, in session.php I am doing
'lifetime' => 10,
I have the session driver set to file. So from what I have read, this sets the idle timeout of the session to 10 minutes.
So what does idle mean in this case? I am assuming it means if no request is sent to the server within 10 minutes it will expire. Is this correct?
Also, how can it tell if no request has been sent within 10 minutes? I have taken a look at the session file within storage, and I do not see any timestamp.
So how exactly does all of this work?
Thanks
Yes you are correct: if you don't send any request after the lifetime config value the session will be destroyed.
The Illuminate\Session\FileSessionHandler class has a gc() function, it is a garbage collector function that has a probability to be called on every request, you can control the chances with the session.lottery config value. This function destroy each session file that has a modified timestamp older than now - lifetime.
You can find the Illuminate\Session\FileSessionHandler class in the file vendor/laravel/framework/src/Illuminate/Session/FileSessionHandler.php if you want to take a look at the source code.
How do I force the ehcache to load all the data from DB once, after that i need to read the values from ehcache.
I am seeing examples in which every new search goes to db first and then next hit from cache.
getProduct("1") - goes to db - ok
getProduct("1") - goes to cache - ok
getProduct("2") - goes to db - **instead i want this from cache**
getProduct("2") - goes to cache - ok
Please advice.
If you want up-front loading of a set of information in the cache, this is something you need your application to trigger.
The cache itself does not know the valid values to getProduct and so cannot prefetch them on its own.
I couldn't find information on the algorithm used by jBoss 7 to generation session IDs and I need to know what characters are possible. I noticed that sometimes the session ID has characters like: + * . etc... This seems different than jBoss 5 which was only alphanumeric.
Can you help me determine what characters are allowed for a jBoss 7 generated session ID?
Thanks
Session ID generation is handled by org.apache.catalina.session.ManagerBase. The general format is as follows:
<encodedSessionId>.<jvmRoute>
ID encoding is based on:
SESSION_ID_ALPHABET = System.getProperty("org.apache.catalina.session.ManagerBase.SESSION_ID_ALPHABET", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_")
The jvmRoute part is usually environment dependent (it may be used for handling session affinity in a cluster).
I have a webservice that stores an authenticated users token in the HttpRuntime.Cache to be used on all subsequent requests. The cached item has a sliding expiration on it of 24 hours.
Secondly I have a vb.net app that is pinging this webservice every 15 seconds. It gets authenticated once, then uses the cached token for all subsequent requests. My problem is that the application appears to lose authentication at random intervals of time less than the 24 hr sliding expiration. However with it getting pinged every 15 sec the authentication should never expire.
I am looking for a way to view the HttpRuntime.cache to try and determine if the problem is in the webservice security methods or within the vb.net app. Can I view the HttpRuntime.cache somehow?
The webservice is part of a web forms site that was built with asp.net 2.0 on a Windows Server 2008.
The name of my key's were unknown as they were system generated guid values with a username as the value. So in order to view a cache collection that was unknown I used a simple loop as follows.
Dim CacheEnum As IDictionaryEnumerator = Cache.GetEnumerator()
While CacheEnum.MoveNext()
Dim cacheItem As String = Server.HtmlEncode(CacheEnum.Entry.Key.ToString())
Dim cacheItem2 As String = Server.HtmlEncode(CacheEnum.Entry.Value.ToString())
Response.Write(cacheItem & ":" & cacheItem2 & "<br />")
End While
Hope this helps others.
First off, HttpRuntime.Cache would not be the best place to store user authentication information. You should instead use HttpContext.Current.Session to store such data. Technically the cache is allowed to "pop" things in it at its own will (whenever it decides to).
If you actually need to use the cache, you can check if your item is in the cache by simply doing:
HttpRuntime.Cache["Key"] == null