I wrote a Windows.Net (2.0) service used to send pager messages to users (via serial ports to third-party equipment).
The service periodically queries the database (OSI PI Historian), parses the values, and decides whether to send a message based on the parsed values.
The service uses a search object (the values of which come from the SQL Server database and is updated every minute) to get the values of user addresses and a message string to send.
The service uses several Threading.Timers to start periodic database calls and send messages.
The service is installed on a computer running Windows 2003 with .Net 2 SP2 installed.
The service works fine for about a week, and then hangs. No exceptions are written to the log (log4net).
I took a few dumps from the server and they all have the same characteristics - the thread launches GC, but hangs indefinitely :
06aaf06c 7c827b99 77e61d1e 00004acc 00000000 ntdll!KiFastSystemCallRet
06aaf070 77e61d1e 00004acc 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc
06aaf0e0 79e8c5f9 00004acc ffffffff 00000000 kernel32!WaitForSingleObjectEx+0xac
06aaf124 79e8c52f 00004acc ffffffff 00000000 mscorwks!PEImage::LoadImage+0x1af
06aaf174 79e8c54e ffffffff 00000000 00000000 mscorwks!CLREvent::WaitEx+0x117
06aaf188 79f2f88f ffffffff 00000000 00000000 mscorwks!CLREvent::Wait+0x17
06aaf1a8 79f2f8ca 7a3b9020 00000000 ffffffff mscorwks!SVR::gc_heap::user_thread_wait+0x50
06aaf1b8 79f2f806 00000000 7a3b8b18 00080101 mscorwks!WKS::gc_heap::wait_to_proceed+0xe
06aaf1cc 79f92f5a 00000000 00000000 00000000 mscorwks!WKS::gc_heap::garbage_collect+0x247
06aaf1f8 79f94e26 00000000 00000000 00000030 mscorwks!WKS::GCHeap::GarbageCollectGeneration+0x1a9
06aaf284 79f926ce 052c75c8 00000030 00000000 mscorwks!WKS::gc_heap::try_allocate_more_space+0x15b
06aaf298 79f92769 052c75c8 00000030 00000000 mscorwks!WKS::gc_heap::allocate_more_space+0x11
06aaf2b8 79e73291 052c75c8 0000002e 00000000 mscorwks!WKS::GCHeap::Alloc+0x3b
06aaf2d4 79e7d8d4 0000002e 00000000 00000000 mscorwks!Alloc+0x60
06aaf310 79e99056 0000000f b456b75e 00001ce3 mscorwks!SlowAllocateString+0x29
06aaf3b4 792bb2c1 00000000 0108082b 00001f40 mscorwks!FramedAllocateString+0xa1
Stack shortened for bravity...
Managed Stack:
ESP EIP
06aaf364 7c82847c [HelperMethodFrame: 06aaf364]
06aaf3bc 792bb2c1 System.String.CreateStringFromEncoding(Byte*, Int32, System.Text.Encoding)
06aaf3dc 792aaf2a System.Text.EncodingNLS.GetString(Byte[], Int32, Int32)
06aaf3fc 6522d131 System.Data.SqlClient.TdsParserStateObject.ReadStringWithEncoding(Int32, System.Text.Encoding, Boolean)
06aaf41c 656ca93e System.Data.SqlClient.TdsParser.ReadSqlStringValue(System.Data.SqlClient.SqlBuffer, Byte, Int32, System.Text.Encoding, Boolean, System.Data.SqlClient.TdsParserStateObject)
06aaf448 6522d925 System.Data.SqlClient.TdsParser.ReadSqlValue(System.Data.SqlClient.SqlBuffer, System.Data.SqlClient.SqlMetaDataPriv, Int32, System.Data.SqlClient.TdsParserStateObject)
06aaf474 656208b7 System.Data.SqlClient.SqlDataReader.ReadColumnData()
06aaf484 65620962 System.Data.SqlClient.SqlDataReader.ReadColumn(Int32, Boolean)
06aaf4b4 65221415 System.Data.SqlClient.SqlDataReader.GetValueInternal(Int32)
06aaf4c8 652213af System.Data.SqlClient.SqlDataReader.GetValue(Int32)
06aaf4f8 65220aec System.Data.SqlClient.SqlDataReader.get_Item(System.String)
06aaf504 03616b81 AlarmEventCollator.DataAccess.GetAllAlarmDetails()
06aaf564 03616a28 AlarmEventCollator.AlarmBuilder.buildLookups()
06aaf590 0361aa89 AlarmEventCollator.AlarmBuilder.pollLookups(System.Object)
06aaf5d0 792a83ff System.Threading._TimerCallback.TimerCallback_Context(System.Object)
06aaf5d8 792e019f System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
06aaf5f0 792a836b System.Threading._TimerCallback.PerformTimerCallback(System.Object)
06aaf77c 79e71b4c [GCFrame: 06aaf77c]
GC usually occurs in database analysis methods. All other managed threads seem to freeze - which will correspond to the GC process.
I would appreciate any pointers. Additional information is available upon request.