Hi
today I installed the mono 2.10.1 on my server, and it seems to run very
nicely. But I found a issue with the project NeatUpload, which I'm not
sure if its a bug from them, or maybe in Mono. The application throws a
exception:
The current thread has not entered the lock in read mode
Description: HTTP 500. Error processing request.
Stack Trace:
System.Threading.SynchronizationLockException: The current thread has not
entered the lock in read mode
at System.Threading.ReaderWriterLockSlim.ExitReadLock () [0x00000] in
<filename unknown>:0
at System.Web.HttpApplicationState.Get (System.String name) [0x00000] in
<filename unknown>:0
at System.Web.HttpApplicationState.get_Item (System.String name) [0x00000] in
<filename unknown>:0
at Brettle.Web.NeatUpload.InProcUploadStateStoreProvider.Load (System.String
postBackID) [0x00000] in <filename unknown>:0
at Brettle.Web.NeatUpload.InProcUploadStateStoreProvider.MergeAndSave
(Brettle.Web.NeatUpload.UploadState uploadState) [0x00000] in <filename
unknown>:0
at Brettle.Web.NeatUpload.AdaptiveUploadStateStoreProvider.MergeAndSave
(Brettle.Web.NeatUpload.UploadState uploadState) [0x00000] in <filename
unknown>:0
at Brettle.Web.NeatUpload.UploadStateStore.MergeAndSave
(Brettle.Web.NeatUpload.UploadState uploadState) [0x00000] in <filename
unknown>:0
at Brettle.Web.NeatUpload.UploadStateStore.UploadState_Changed (System.Object
sender, System.EventArgs args) [0x00000] in <filename unknown>:0
at Brettle.Web.NeatUpload.UploadState.OnChanged () [0x00000] in <filename
unknown>:0
at Brettle.Web.NeatUpload.UploadState.set_Status (UploadStatus value)
[0x00000] in <filename unknown>:0
at Brettle.Web.NeatUpload.UploadHttpModule.Application_ResolveRequestCache
(System.Object sender, System.EventArgs e) [0x00000] in <filename unknown>:0
at System.Web.HttpApplication+<RunHooks>c__Iterator2.MoveNext () [0x00000] in
<filename unknown>:0
at System.Web.HttpApplication+<Pipeline>c__Iterator3.MoveNext () [0x00000] in
<filename unknown>:0
at System.Web.HttpApplication.Tick () [0x00000] in <filename unknown>:0
________________________________________________________________________
Version information: Mono Runtime Version: 2.10.1 (tarball Mon Feb 28
09:35:03 CET 2011); ASP.NET Version: 2.0.50727.1433
I checked the source of NeatUpload code, and here is what they do:
public class InProcUploadStateStoreProvider : UploadStateStoreProvider
{
public override string Description { get { return "Stores
UploadState objects in the HttpApplicationState of the current
process."; } }
private static string KeyPrefix =
"NeatUpload_InProcUploadState_";
public override UploadState Load(string postBackID)
{
string key = KeyPrefix + postBackID;
return Application[key] as UploadState;
}
public override void MergeAndSave(UploadState uploadState)
{
string key = KeyPrefix + uploadState.PostBackID;
Application.Lock();
try
{
UploadState storedUploadState =
Load(uploadState.PostBackID);
Merge(uploadState, storedUploadState);
Application[key] = uploadState;
}
finally
{
Application.UnLock();
}
}
private HttpApplicationState Application
{
get
{
HttpContext ctx = HttpContext.Current;
if (ctx != null)
return ctx.Application;
if (ThreadStaticApplication != null)
return ThreadStaticApplication;
throw new
NullReferenceException("ThreadStaticApplication == null");
}
}
I removed some not important code here. To solve the issue changed the
code in MergeAndSave() to :
public override void MergeAndSave(UploadState uploadState)
{
string key = KeyPrefix + uploadState.PostBackID;
HttpApplicationState app = Application;
lock (app) {
UploadState storedUploadState =
Load(uploadState.PostBackID);
Merge(uploadState, storedUploadState);
Application[key] = uploadState;
}
}
And this seems to work nicely. But, could this be a bug in Mono? I
thought I better ask first, cause I'm not familiar with using
Application.Lock in this situation. In other words, I never use it, so
my workaround should be not problem.
With kind regards,
Peter
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