FileSystemWatch ers and CacheDependency

[daniel]

Hi,
I am developing an application that requires me to set up file system
watchers on directories on a network drive, as well as set up
CacheDependenci es in the same location for my System.Web.Cach ing.Cache. When
i set up the file watchers and then create the cache dependency i receive an
Exception (AccessViolatio nError - Attempted to read or write protected
memory). I have included a the stack trace from the exception at the end of
this post. This only occurs when i am creating a large number of file
watchers ( i have found the the for my PC i can only create 48!). The
following is a sample application i built which consistantly throws the
exception( note that when i copy the directory structe from the network drive
to a local drive the function works flawlessly ).

List<FileSystem Watcherwatchers = new List<FileSystem Watcher>();
foreach( string directory in Directory.GetDi rectories(
@"\\itchy\image link\Books\V3Bo oks" ) )
{
FileSystemWatch er watcher = new FileSystemWatch er( directory );
watcher.Deleted += new FileSystemEvent Handler( watcher_Deleted );
watcher.Created += new FileSystemEvent Handler( watcher_Created );
watcher.Renamed += new RenamedEventHan dler( watcher_Renamed );
watcher.Changed += new FileSystemEvent Handler( watcher_Changed );
watcher.EnableR aisingEvents = true;
watchers.Add( watcher );
}
CacheDependency depencency2 = new CacheDependency (
@"\\itchy\image link\Books\V3Bo oks\man.lst" );
Partial Stack Trace:

at System.Web.Unsa feNativeMethods .RaiseFileMonit oringEventlogEv ent(String
eventInfo, String path, String appVirtualPath, Int32 hr)
at System.Web.File ChangesMonitor. CreateFileMonit oringException( Int32 hr,
String path)
at System.Web.DirM onCompletion..c tor(DirectoryMo nitor dirMon, String dir,
Boolean watchSubtree, UInt32 notifyFilter)
at System.Web.Dire ctoryMonitor.St artMonitoring()
at System.Web.Dire ctoryMonitor.St artMonitoringFi le(String file,
FileChangeEvent Handler callback, String alias)
at System.Web.File ChangesMonitor. StartMonitoring Path(String alias,
FileChangeEvent Handler callback, FileAttributesD ata& fad)
at System.Web.Cach ing.CacheDepend ency.Init(Boole an isPublic, String[]
filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime
utcStart)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename, DateTime start)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename)
at WindowsApplicat ion4.Form1.Load TargetFolder() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Form1. cs:line 52
at WindowsApplicat ion4.Program.Ma in() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Progra m.cs:line 17
at System.AppDomai n.nExecuteAssem bly(Assembly assembly, String[] args)
at System.AppDomai n.ExecuteAssemb ly(String assemblyFile, Evidence
assemblySecurit y, String[] args)
at Microsoft.Visua lStudio.Hosting Process.HostPro c.RunUsersAssem bly()
at System.Threadin g.ThreadHelper. ThreadStart_Con text(Object state)
at System.Threadin g.ExecutionCont ext.Run(Executi onContext executionContex t,
ContextCallback callback, Object state)
at System.Threadin g.ThreadHelper. ThreadStart()

Thanks,
Daniel

[Michael]

daniel,

Not really answering your question but I am wondering why you don't just
create one FileSystemWatch er on "\\itchy\imagel ink\Books\V3Boo ks" and set the
IncludeSubdirec tories property?

Another option might be to map a drive to "\\itchy\imagel ink\Books\V3Boo ks"
and then enumerate the directories through the mapped drive.

Michael

"daniel" wrote:

Hi,
I am developing an application that requires me to set up file system
watchers on directories on a network drive, as well as set up
CacheDependenci es in the same location for my System.Web.Cach ing.Cache. When
i set up the file watchers and then create the cache dependency i receive an
Exception (AccessViolatio nError - Attempted to read or write protected
memory). I have included a the stack trace from the exception at the end of
this post. This only occurs when i am creating a large number of file
watchers ( i have found the the for my PC i can only create 48!). The
following is a sample application i built which consistantly throws the
exception( note that when i copy the directory structe from the network drive
to a local drive the function works flawlessly ).

List<FileSystem Watcherwatchers = new List<FileSystem Watcher>();
foreach( string directory in Directory.GetDi rectories(
@"\\itchy\image link\Books\V3Bo oks" ) )
{
FileSystemWatch er watcher = new FileSystemWatch er( directory );
watcher.Deleted += new FileSystemEvent Handler( watcher_Deleted );
watcher.Created += new FileSystemEvent Handler( watcher_Created );
watcher.Renamed += new RenamedEventHan dler( watcher_Renamed );
watcher.Changed += new FileSystemEvent Handler( watcher_Changed );
watcher.EnableR aisingEvents = true;
watchers.Add( watcher );
}
CacheDependency depencency2 = new CacheDependency (
@"\\itchy\image link\Books\V3Bo oks\man.lst" );
Partial Stack Trace:

at System.Web.Unsa feNativeMethods .RaiseFileMonit oringEventlogEv ent(String
eventInfo, String path, String appVirtualPath, Int32 hr)
at System.Web.File ChangesMonitor. CreateFileMonit oringException( Int32 hr,
String path)
at System.Web.DirM onCompletion..c tor(DirectoryMo nitor dirMon, String dir,
Boolean watchSubtree, UInt32 notifyFilter)
at System.Web.Dire ctoryMonitor.St artMonitoring()
at System.Web.Dire ctoryMonitor.St artMonitoringFi le(String file,
FileChangeEvent Handler callback, String alias)
at System.Web.File ChangesMonitor. StartMonitoring Path(String alias,
FileChangeEvent Handler callback, FileAttributesD ata& fad)
at System.Web.Cach ing.CacheDepend ency.Init(Boole an isPublic, String[]
filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime
utcStart)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename, DateTime start)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename)
at WindowsApplicat ion4.Form1.Load TargetFolder() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Form1. cs:line 52
at WindowsApplicat ion4.Program.Ma in() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Progra m.cs:line 17
at System.AppDomai n.nExecuteAssem bly(Assembly assembly, String[] args)
at System.AppDomai n.ExecuteAssemb ly(String assemblyFile, Evidence
assemblySecurit y, String[] args)
at Microsoft.Visua lStudio.Hosting Process.HostPro c.RunUsersAssem bly()
at System.Threadin g.ThreadHelper. ThreadStart_Con text(Object state)
at System.Threadin g.ExecutionCont ext.Run(Executi onContext executionContex t,
ContextCallback callback, Object state)
at System.Threadin g.ThreadHelper. ThreadStart()

Thanks,
Daniel

[daniel]

Michael,

The number of file watchers that causes the crash seems to be completely
intermitant, my example may be a bit overly complex but i hav also tried
having just one file watcher on the network directory and some times it
crashes sometimes it doesn't. It also seems to make no difference whether it
is a mapped network drive or not.

Also, the number of filewatchers differs between locations that i map to..
on some network paths i can create several file watchers before a crash, on
other servers only one...

I have tried a mapping to servers with various operating systems including
windows xp, win 2000 and 2003 all with the same results.

Regards
Daniel

"Michael" wrote:

daniel,

Not really answering your question but I am wondering why you don't just
create one FileSystemWatch er on "\\itchy\imagel ink\Books\V3Boo ks" and set the
IncludeSubdirec tories property?

Another option might be to map a drive to "\\itchy\imagel ink\Books\V3Boo ks"
and then enumerate the directories through the mapped drive.

Michael

"daniel" wrote:

Hi,
I am developing an application that requires me to set up file system
watchers on directories on a network drive, as well as set up
CacheDependenci es in the same location for my System.Web.Cach ing.Cache. When
i set up the file watchers and then create the cache dependency i receive an
Exception (AccessViolatio nError - Attempted to read or write protected
memory). I have included a the stack trace from the exception at the end of
this post. This only occurs when i am creating a large number of file
watchers ( i have found the the for my PC i can only create 48!). The
following is a sample application i built which consistantly throws the
exception( note that when i copy the directory structe from the network drive
to a local drive the function works flawlessly ).

List<FileSystem Watcherwatchers = new List<FileSystem Watcher>();
foreach( string directory in Directory.GetDi rectories(
@"\\itchy\image link\Books\V3Bo oks" ) )
{
FileSystemWatch er watcher = new FileSystemWatch er( directory );
watcher.Deleted += new FileSystemEvent Handler( watcher_Deleted );
watcher.Created += new FileSystemEvent Handler( watcher_Created );
watcher.Renamed += new RenamedEventHan dler( watcher_Renamed );
watcher.Changed += new FileSystemEvent Handler( watcher_Changed );
watcher.EnableR aisingEvents = true;
watchers.Add( watcher );
}
CacheDependency depencency2 = new CacheDependency (
@"\\itchy\image link\Books\V3Bo oks\man.lst" );
Partial Stack Trace:

at System.Web.Unsa feNativeMethods .RaiseFileMonit oringEventlogEv ent(String
eventInfo, String path, String appVirtualPath, Int32 hr)
at System.Web.File ChangesMonitor. CreateFileMonit oringException( Int32 hr,
String path)
at System.Web.DirM onCompletion..c tor(DirectoryMo nitor dirMon, String dir,
Boolean watchSubtree, UInt32 notifyFilter)
at System.Web.Dire ctoryMonitor.St artMonitoring()
at System.Web.Dire ctoryMonitor.St artMonitoringFi le(String file,
FileChangeEvent Handler callback, String alias)
at System.Web.File ChangesMonitor. StartMonitoring Path(String alias,
FileChangeEvent Handler callback, FileAttributesD ata& fad)
at System.Web.Cach ing.CacheDepend ency.Init(Boole an isPublic, String[]
filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime
utcStart)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename, DateTime start)
at System.Web.Cach ing.CacheDepend ency..ctor(Stri ng filename)
at WindowsApplicat ion4.Form1.Load TargetFolder() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Form1. cs:line 52
at WindowsApplicat ion4.Program.Ma in() in
D:\MyProjects\W indowsApplicati on4\WindowsAppl ication4\Progra m.cs:line 17
at System.AppDomai n.nExecuteAssem bly(Assembly assembly, String[] args)
at System.AppDomai n.ExecuteAssemb ly(String assemblyFile, Evidence
assemblySecurit y, String[] args)
at Microsoft.Visua lStudio.Hosting Process.HostPro c.RunUsersAssem bly()
at System.Threadin g.ThreadHelper. ThreadStart_Con text(Object state)
at System.Threadin g.ExecutionCont ext.Run(Executi onContext executionContex t,
ContextCallback callback, Object state)
at System.Threadin g.ThreadHelper. ThreadStart()

Thanks,
Daniel