Disclaimer: Most of the content for this post come from an amazing blog post by , which was the only source I could find on how to troubleshoot this issue, I am posting it here with some small modifications to fit a different scenario where we were not clear on which pool was having the leaking connections

We started with several operations failing with this error

CLR exception type: System.InvalidOperationException

    "Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached."

 The first step was to collect a memory dump, and start analyzing it, first we need to find all connection pools

0:166> !Name2EE System.Data.dll System.Data.ProviderBase.DbConnectionPool

Module:      00007ffbc78f4520

Assembly:    System.Data.dll

Token:       0000000002000229

MethodTable: 00007ffbc8603f28

EEClass:     00007ffbc85e7a88

Name:        System.Data.ProviderBase.DbConnectionPool

 

Then dump information about all connection pools using the MT we got from the previous step

0:166> .foreach (foo {!DumpHeap -short -MT 00007ffbc8603f28}) {.echo foo; !do foo}

0000003c7218fd38

Name:        System.Data.ProviderBase.DbConnectionPool

MethodTable: 00007ffbc8603f28

EEClass:     00007ffbc85e7a88

Size:        168(0xa8) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  4000e73       80         System.Int32  1 instance           170000 _cleanupWait

00007ffbc860bbb0  4000e74        8 ...ctionPoolIdentity  0 instance 0000003cf1fa4508 _identity

00007ffbc8602b90  4000e75       10 ...ConnectionFactory  0 instance 0000003f71fcb8b0 _connectionFactory

00007ffbc86025c8  4000e76       18 ...nnectionPoolGroup  0 instance 0000003c7218f780 _connectionPoolGroup

00007ffbc860b500  4000e77       20 ...nPoolGroupOptions  0 instance 0000003c7218f758 _connectionPoolGroupOptions

00007ffbc862e0f8  4000e78       28 ...nPoolProviderInfo  0 instance 0000000000000000 _connectionPoolProviderInfo

00007ffbc8603dd0  4000e79       84         System.Int32  1 instance                1 _state

00007ffbc862e188  4000e7a       30 ...al, System.Data]]  0 instance 0000003c7218fde0 _stackOld

00007ffbc862e188  4000e7b       38 ...al, System.Data]]  0 instance 0000003c7218fe00 _stackNew

00007ffbc862fb38  4000e7c       40 ...on, System.Data]]  0 instance 0000003c7218fe20 _pendingOpens

00007ffbc6d9f6f0  4000e7d       88         System.Int32  1 instance                0 _pendingOpensWaiting

00007ffbc6f0a188  4000e7e       48 ...ding.WaitCallback  0 instance 0000003c72190510 _poolCreateRequest

00007ffbc6d9f6f0  4000e7f       8c         System.Int32  1 instance                0 _waitCount

00007ffbc86504c0  4000e80       50 ...l+PoolWaitHandles  0 instance 0000003c7218ffe8 _waitHandles

00007ffbc6de5290  4000e81       58     System.Exception  0 instance 0000003ff2c89558 _resError

00007ffbc6d9c620  4000e82       9c       System.Boolean  1 instance                0 _errorOccurred

00007ffbc6d9f6f0  4000e83       90         System.Int32  1 instance             5000 _errorWait

00007ffbc7010048  4000e84       60 ...m.Threading.Timer  0 instance 0000000000000000 _errorTimer

00007ffbc7010048  4000e85       68 ...m.Threading.Timer  0 instance 0000003c72190590 _cleanupTimer

00007ffbc8650c98  4000e86       70 ...tedConnectionPool  0 instance 0000003c72190498 _transactedConnectionPool

00007ffbc8650580  4000e87       78 ...al, System.Data]]  0 instance 0000003c72190130 _objectList

00007ffbc6d9f6f0  4000e88       94         System.Int32  1 instance                4 _totalObjects

00007ffbc6d9f6f0  4000e8a       98         System.Int32  1 instance                3 _objectID

00007ffbc8304be8  4000e72      b98        System.Random  0   static 0000003cf1fa73c0 _random

00007ffbc6d9f6f0  4000e89      a00         System.Int32  1   static             5117 _objectTypeCount

 The previous one does not seem interesting, since it has only 4 connections in the pool and the wait count is zero. Moving on to the next pool 

0000003c7360fec8

Name:        System.Data.ProviderBase.DbConnectionPool

MethodTable: 00007ffbc8603f28

EEClass:     00007ffbc85e7a88

Size:        168(0xa8) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  4000e73       80         System.Int32  1 instance           140000 _cleanupWait

00007ffbc860bbb0  4000e74        8 ...ctionPoolIdentity  0 instance 0000003cf1fa4508 _identity

00007ffbc8602b90  4000e75       10 ...ConnectionFactory  0 instance 0000003f71fcb8b0 _connectionFactory

00007ffbc86025c8  4000e76       18 ...nnectionPoolGroup  0 instance 0000003f7215b290 _connectionPoolGroup

00007ffbc860b500  4000e77       20 ...nPoolGroupOptions  0 instance 0000003f7215b268 _connectionPoolGroupOptions

00007ffbc862e0f8  4000e78       28 ...nPoolProviderInfo  0 instance 0000000000000000 _connectionPoolProviderInfo

00007ffbc8603dd0  4000e79       84         System.Int32  1 instance                1 _state

00007ffbc862e188  4000e7a       30 ...al, System.Data]]  0 instance 0000003c7360ff70 _stackOld

00007ffbc862e188  4000e7b       38 ...al, System.Data]]  0 instance 0000003c7360ff90 _stackNew

00007ffbc862fb38  4000e7c       40 ...on, System.Data]]  0 instance 0000003c7360ffb0 _pendingOpens

00007ffbc6d9f6f0  4000e7d       88         System.Int32  1 instance                0 _pendingOpensWaiting

00007ffbc6f0a188  4000e7e       48 ...ding.WaitCallback  0 instance 0000003c736106a0 _poolCreateRequest

00007ffbc6d9f6f0  4000e7f       8c         System.Int32  1 instance                2 _waitCount

00007ffbc86504c0  4000e80       50 ...l+PoolWaitHandles  0 instance 0000003c73610178 _waitHandles

00007ffbc6de5290  4000e81       58     System.Exception  0 instance 0000000000000000 _resError

00007ffbc6d9c620  4000e82       9c       System.Boolean  1 instance                0 _errorOccurred

00007ffbc6d9f6f0  4000e83       90         System.Int32  1 instance             5000 _errorWait

00007ffbc7010048  4000e84       60 ...m.Threading.Timer  0 instance 0000000000000000 _errorTimer

00007ffbc7010048  4000e85       68 ...m.Threading.Timer  0 instance 0000003c73610720 _cleanupTimer

00007ffbc8650c98  4000e86       70 ...tedConnectionPool  0 instance 0000003c73610628 _transactedConnectionPool

00007ffbc8650580  4000e87       78 ...al, System.Data]]  0 instance 0000003c736102c0 _objectList

00007ffbc6d9f6f0  4000e88       94         System.Int32  1 instance              100 _totalObjects

00007ffbc6d9f6f0  4000e8a       98         System.Int32  1 instance             3541 _objectID

00007ffbc8304be8  4000e72      b98        System.Random  0   static 0000003cf1fa73c0 _random

00007ffbc6d9f6f0  4000e89      a00         System.Int32  1   static             5117 _objectTypeCount

 This one definitely seems to be it, the number of connections in the pool is 100 which is our limit, and there are 2 objects waiting, so moving on to analyzing with more details based on Remi's instructions  

0:166> !do 0000003c7360fec8

Name:        System.Data.ProviderBase.DbConnectionPool

MethodTable: 00007ffbc8603f28

EEClass:     00007ffbc85e7a88

Size:        168(0xa8) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  4000e73       80         System.Int32  1 instance           140000 _cleanupWait

00007ffbc860bbb0  4000e74        8 ...ctionPoolIdentity  0 instance 0000003cf1fa4508 _identity

00007ffbc8602b90  4000e75       10 ...ConnectionFactory  0 instance 0000003f71fcb8b0 _connectionFactory

00007ffbc86025c8  4000e76       18 ...nnectionPoolGroup  0 instance 0000003f7215b290 _connectionPoolGroup

00007ffbc860b500  4000e77       20 ...nPoolGroupOptions  0 instance 0000003f7215b268 _connectionPoolGroupOptions

00007ffbc862e0f8  4000e78       28 ...nPoolProviderInfo  0 instance 0000000000000000 _connectionPoolProviderInfo

00007ffbc8603dd0  4000e79       84         System.Int32  1 instance                1 _state

00007ffbc862e188  4000e7a       30 ...al, System.Data]]  0 instance 0000003c7360ff70 _stackOld

00007ffbc862e188  4000e7b       38 ...al, System.Data]]  0 instance 0000003c7360ff90 _stackNew

00007ffbc862fb38  4000e7c       40 ...on, System.Data]]  0 instance 0000003c7360ffb0 _pendingOpens

00007ffbc6d9f6f0  4000e7d       88         System.Int32  1 instance                0 _pendingOpensWaiting

00007ffbc6f0a188  4000e7e       48 ...ding.WaitCallback  0 instance 0000003c736106a0 _poolCreateRequest

00007ffbc6d9f6f0  4000e7f       8c         System.Int32  1 instance                2 _waitCount

00007ffbc86504c0  4000e80       50 ...l+PoolWaitHandles  0 instance 0000003c73610178 _waitHandles

00007ffbc6de5290  4000e81       58     System.Exception  0 instance 0000000000000000 _resError

00007ffbc6d9c620  4000e82       9c       System.Boolean  1 instance                0 _errorOccurred

00007ffbc6d9f6f0  4000e83       90         System.Int32  1 instance             5000 _errorWait

00007ffbc7010048  4000e84       60 ...m.Threading.Timer  0 instance 0000000000000000 _errorTimer

00007ffbc7010048  4000e85       68 ...m.Threading.Timer  0 instance 0000003c73610720 _cleanupTimer

00007ffbc8650c98  4000e86       70 ...tedConnectionPool  0 instance 0000003c73610628 _transactedConnectionPool

00007ffbc8650580  4000e87       78 ...al, System.Data]]  0 instance 0000003c736102c0 _objectList  <-- This is the list of connections in this connection pool

00007ffbc6d9f6f0  4000e88       94         System.Int32  1 instance              100 _totalObjects

00007ffbc6d9f6f0  4000e8a       98         System.Int32  1 instance             3541 _objectID

00007ffbc8304be8  4000e72      b98        System.Random  0   static 0000003cf1fa73c0 _random

00007ffbc6d9f6f0  4000e89      a00         System.Int32  1   static             5117 _objectTypeCount

 Now we can inspect the objectlist

 0:166> !do 0000003c736102c0

Name:        System.Collections.Generic.List`1[[System.Data.ProviderBase.DbConnectionInternal, System.Data]]

MethodTable: 00007ffbc8650580

EEClass:     00007ffbc6e423b8

Size:        40(0x28) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9ba28  4000cd1        8      System.Object[]  0 instance 0000003c736102e8 _items  <-- Find the array of items

00007ffbc6d9f6f0  4000cd2       18         System.Int32  1 instance              100 _size

00007ffbc6d9f6f0  4000cd3       1c         System.Int32  1 instance             2126 _version

00007ffbc6d96080  4000cd4       10        System.Object  0 instance 0000000000000000 _syncRoot

00007ffbc6d9ba28  4000cd5        8      System.Object[]  0   static  <no information>

 Then Dump the contents of the array

 0:118> !da 0000003c736102e8

Name:        System.Data.ProviderBase.DbConnectionInternal[]

MethodTable: 00007ffbc6d9ba28

EEClass:     00007ffbc6d9b980

Size:        832(0x340) bytes

Array:       Rank 1, Number of elements 100, Type CLASS

Element Methodtable: 00007ffbc8602030

[0] 0000003ff605c8b8

[1] 0000003f7660b270

[2] 0000003ef6d2e860

[3] 0000003df7e341b0

[4] 0000003ef73b3280

[5] 0000003ef73b5260

[6] 0000003f77ad5c20

[7] 0000003e76deffb8

[8] 0000003cf7894fc0

 ...

 Now You can start inspecting the different items in the array, to see if they all are being used by the same query using Remi's instructions

0:118> !do 0000003ff605c8b8

Name:        System.Data.SqlClient.SqlInternalConnectionTds

MethodTable: 00007ffbc86289d8

EEClass:     00007ffbc861d270

Size:        304(0x130) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  40008bb       38         System.Int32  1 instance            18391 _objectID

00007ffbc6d9c620  40008be       44       System.Boolean  1 instance                0 _allowSetConnectionString

00007ffbc6d9c620  40008bf       45       System.Boolean  1 instance                1 _hidePassword

00007ffbc8601ed8  40008c0       3c         System.Int32  1 instance                1 _state

00007ffbc6fca230  40008c1        8 System.WeakReference  0 instance 0000003ff605ca58 _owningObject

00007ffbc8603f28  40008c2       10 ....DbConnectionPool  0 instance 0000003c7360fec8 _connectionPool

00007ffbc8605050  40008c3       18 ...ctionPoolCounters  0 instance 0000003f71fcb8f0 _performanceCounters

00007ffbc86816a0  40008c4       20 ...ferenceCollection  0 instance 0000003ff6061b38 _referenceCollection

00007ffbc6d9f6f0  40008c5       40         System.Int32  1 instance                0 _pooledCount

00007ffbc6d9c620  40008c6       46       System.Boolean  1 instance                0 _connectionIsDoomed

00007ffbc6d9c620  40008c7       47       System.Boolean  1 instance                0 _cannotBePooled

00007ffbc6d9c620  40008c8       48       System.Boolean  1 instance                0 _isInStasis

00007ffbc6fce4f0  40008c9       50      System.DateTime  1 instance 0000003ff605c908 _createTime

00007ffbc862e010  40008ca       28 ...tions.Transaction  0 instance 0000000000000000 _enlistedTransaction

00007ffbc862e010  40008cb       30 ...tions.Transaction  0 instance 0000000000000000 _enlistedTransactionOriginal

00007ffbc6d9f6f0  40008ba      700         System.Int32  1   static            18584 _objectTypeCount

00007ffbc860b308  40008bc      628 ...teChangeEventArgs  0   static 0000003c71fb8d78 StateChangeClosed

00007ffbc860b308  40008bd      630 ...teChangeEventArgs  0   static 0000003c71fb8d90 StateChangeOpen

00007ffbc86019e8  400127f       58 ...lConnectionString  0 instance 0000003f7215acf8 _connectionOptions

00007ffbc6d9c620  4001280       88       System.Boolean  1 instance                0 _isEnlistedInTransaction

00007ffbc6e30eb0  4001281       60        System.Byte[]  0 instance 0000000000000000 _promotedDTCToken

00007ffbc6e30eb0  4001282       68        System.Byte[]  0 instance 0000000000000000 _whereAbouts

00007ffbc6de46f0  4001283       70        System.String  0 instance 0000003ff605da20 <CurrentDatabase>k__BackingField

00007ffbc6de46f0  4001284       78        System.String  0 instance 0000003f7215ae18 <CurrentDataSource>k__BackingField

00007ffbc884a318  4001285       80 ...egatedTransaction  0 instance 0000000000000000 <DelegatedTransaction>k__BackingField

00007ffbc860d1b0  40012a7       90 ...GroupProviderInfo  0 instance 0000003f7215b2d8 _poolGroupProviderInfo

00007ffbc8629c78  40012a8       98 ...lClient.TdsParser  0 instance 0000003ff605d4b8 _parser

00007ffbc865e0e8  40012a9       a0 ...lient.SqlLoginAck  0 instance 0000003ff605daf0 _loginAck

00007ffbc84cb330  40012aa       a8 ...ent.SqlCredential  0 instance 0000003cf2193680 _credential

00007ffbc6d9c620  40012ab       89       System.Boolean  1 instance                1 _sessionRecoveryRequested

00007ffbc6d9c620  40012ac       8a       System.Boolean  1 instance                1 _sessionRecoveryAcknowledged

00007ffbc86558e0  40012ad       b0 ...lient.SessionData  0 instance 0000003ff605ca70 _currentSessionData

00007ffbc86558e0  40012ae       b8 ...lient.SessionData  0 instance 0000000000000000 _recoverySessionData

00007ffbc6d9c620  40012af       8b       System.Boolean  1 instance                1 _fConnectionOpen

00007ffbc6d9c620  40012b0      110       System.Boolean  1 instance                1 _fResetConnection

00007ffbc6de46f0  40012b1       c0        System.String  0 instance 0000003ff605da20 _originalDatabase

00007ffbc6de46f0  40012b2       c8        System.String  0 instance 0000000000000000 _currentFailoverPartner

00007ffbc6de46f0  40012b3       d0        System.String  0 instance 0000003ff605dac0 _originalLanguage

00007ffbc6de46f0  40012b4       d8        System.String  0 instance 0000003ff605dac0 _currentLanguage

00007ffbc6d9f6f0  40012b5       8c         System.Int32  1 instance             8000 _currentPacketSize

00007ffbc6d9f6f0  40012b6      108         System.Int32  1 instance                0 _asyncCommandCount

00007ffbc6de46f0  40012b7       e0        System.String  0 instance 0000003c71fa1450 _instanceName

00007ffbc860bbb0  40012b8       e8 ...ctionPoolIdentity  0 instance 0000000000000000 _identity

00007ffbc8656558  40012b9       f0 ...Tds+SyncAsyncLock  0 instance 0000003ff605c9e8 _parserLock

00007ffbc6d9f6f0  40012ba      10c         System.Int32  1 instance               -1 _threadIdOwningParserLock

00007ffbc8656970  40012bb       f8 ...eoutErrorInternal  0 instance 0000003ff605d3c8 timeoutErrorInternal

00007ffbc6e3fb58  40012bc      118          System.Guid  1 instance 0000003ff605c9d0 _clientConnectionId

00007ffbc8656ea0  40012bd      100 ...lient.RoutingInfo  0 instance 0000000000000000 _routingInfo

 Now Dump the _parser member

 0:118> !do 0000003ff605d4b8

Name:        System.Data.SqlClient.TdsParser

MethodTable: 00007ffbc8629c78

EEClass:     00007ffbc861d2f8

Size:        160(0xa0) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  400151a       70         System.Int32  1 instance            18394 _objectID

00007ffbc862b328  400151c        8 ...ParserStateObject  0 instance 0000003ff605d558 _physicalStateObj

00007ffbc862b328  400151d       10 ...ParserStateObject  0 instance 0000000000000000 _pMarsPhysicalConObj

00007ffbc86299d0  400151e       74         System.Int32  1 instance                2 _state

00007ffbc6de46f0  400151f       18        System.String  0 instance 0000003f7215ae18 _server

00007ffbc6d9c620  4001520       88       System.Boolean  1 instance                0 _fResetConnection

00007ffbc6d9c620  4001521       89       System.Boolean  1 instance                0 _fPreserveTransaction

00007ffbc865d050  4001522       20 ...ient.SqlCollation  0 instance 0000003ff605daa8 _defaultCollation

00007ffbc6d9f6f0  4001523       78         System.Int32  1 instance             1252 _defaultCodePage

00007ffbc6d9f6f0  4001524       7c         System.Int32  1 instance             1033 _defaultLCID

00007ffbc7018568  4001525       28 System.Text.Encoding  0 instance 0000003c71fc23b0 _defaultEncoding

00007ffbc8629b20  4001527       80         System.Int32  1 instance                1 _encryptionOption

00007ffbc860ef98  4001528       30 ...ternalTransaction  0 instance 0000000000000000 _currentTransaction

00007ffbc860ef98  4001529       38 ...ternalTransaction  0 instance 0000000000000000 _pendingTransaction

00007ffbc6de0630  400152a       68         System.Int64  1 instance 0 _retainedTransactionId

00007ffbc6d9f6f0  400152b       84         System.Int32  1 instance                1 _nonTransactedOpenResultCount

00007ffbc86289d8  400152c       40 ...rnalConnectionTds  0 instance 0000003ff605c8b8 _connHandler

00007ffbc6d9c620  400152d       8a       System.Boolean  1 instance                0 _fMARS

00007ffbc6d9c620  400152e       8b       System.Boolean  1 instance                0 _loginWithFailover

00007ffbc73f0698  400152f       48 ...ng.AutoResetEvent  0 instance 0000000000000000 _resetConnectionEvent

00007ffbc862b4e8  4001530       50 ...ParserSessionPool  0 instance 0000000000000000 _sessionPool

00007ffbc6d9c620  4001531       8c       System.Boolean  1 instance                1 _isShiloh

00007ffbc6d9c620  4001532       8d       System.Boolean  1 instance                1 _isShilohSP1

00007ffbc6d9c620  4001533       8e       System.Boolean  1 instance                1 _isYukon

00007ffbc6d9c620  4001534       8f       System.Boolean  1 instance                1 _isKatmai

00007ffbc6d9c620  4001535       90       System.Boolean  1 instance                1 _isDenali

00007ffbc6e30eb0  4001536       58        System.Byte[]  0 instance 0000000000000000 _sniSpnBuffer

00007ffbc86281b0  4001537       60 ...ent.SqlStatistics  0 instance 0000000000000000 _statistics

00007ffbc6d9c620  4001538       91       System.Boolean  1 instance                0 _statisticsIsInTransaction

00007ffbc6d9c620  400153f       92       System.Boolean  1 instance                0 _asyncWrite

00007ffbc6d9f6f0  4001519      a60         System.Int32  1   static            18587 _objectTypeCount

00007ffbc6f0b5d0  400151b     1130 ...eading.Tasks.Task  0   static 0000000000000000 completedTask

00007ffbc8629b20  4001526      a64         System.Int32  1   static                0 _sniSupportedEncryptionOption

00007ffbc6e30eb0  4001539     1138        System.Byte[]  0   static 0000003c71fbec48 s_nicAddress

00007ffbc6d9c620  400153a      a6c       System.Boolean  1   static                0 s_fSSPILoaded

00007ffbc6d9fe78  400153b      a68        System.UInt32  1   static                0 s_maxSSPILength

00007ffbc6e30eb0  400153c     1140        System.Byte[]  0   static 0000003cf1fc24d0 s_longDataHeader

00007ffbc6d96080  400153d     1148        System.Object  0   static 0000003cf1fc2508 s_tdsParserLock

00007ffbc6e30eb0  400153e     1150        System.Byte[]  0   static 0000003cf1fc2520 s_xmlMetadataSubstituteSequence

00007ffbc86575c8  4001540     1158 ...rd, System.Data]]  0   static 0000003cf1fc2588 __tvpEmptyValue

 Then dump the _physicalStateObj

 0:118> !do 0000003ff605d558

Name:        System.Data.SqlClient.TdsParserStateObject

MethodTable: 00007ffbc862b328

EEClass:     00007ffbc861d750

Size:        440(0x1b8) bytes

File:        D:\Windows\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

Fields:

              MT    Field   Offset                 Type VT     Attr            Value Name

00007ffbc6d9f6f0  40015ea      130         System.Int32  1 instance            18394 _objectID

00007ffbc8629c78  40015eb        8 ...lClient.TdsParser  0 instance 0000003ff605d4b8 _parser

00007ffbc862a388  40015ec       10 ...lClient.SNIHandle  0 instance 0000003ff605d8b8 _sessionHandle

00007ffbc6fca230  40015ed       18 System.WeakReference  0 instance 0000003ff605d710 _owner

00007ffbc8682960  40015ee       20 ...eader+SharedState  0 instance 0000003c77292e50 _readerState

00007ffbc6d9f6f0  40015ef      134         System.Int32  1 instance                0 _activateCount

00007ffbc6d9f6f0  40015f0      138         System.Int32  1 instance                8 _inputHeaderLen

00007ffbc6d9f6f0  40015f1      13c         System.Int32  1 instance                8 _outputHeaderLen

00007ffbc6e30eb0  40015f2       28        System.Byte[]  0 instance 0000003ff605fab8 _outBuff

00007ffbc6d9f6f0  40015f3      140         System.Int32  1 instance                8 _outBytesUsed

00007ffbc6e30eb0  40015f4       30        System.Byte[]  0 instance 0000003ff605db60 _inBuff

00007ffbc6d9f6f0  40015f5      144         System.Int32  1 instance             7823 _inBytesUsed

00007ffbc6d9f6f0  40015f6      148         System.Int32  1 instance             7841 _inBytesRead

00007ffbc6d9f6f0  40015f7      14c         System.Int32  1 instance               18 _inBytesPacket

00007ffbc6d9e008  40015f8      17c          System.Byte  1 instance                3 _outputMessageType

00007ffbc6d9e008  40015f9      17d          System.Byte  1 instance                1 _messageStatus

00007ffbc6d9e008  40015fa      17e          System.Byte  1 instance                1 _outputPacketNumber

00007ffbc6d9c620  40015fb      17f       System.Boolean  1 instance                1 _pendingData

00007ffbc6d9c620  40015fc      180       System.Boolean  1 instance                0 _fResetEventOwned

00007ffbc6d9c620  40015fd      181       System.Boolean  1 instance                0 _fResetConnectionSent

00007ffbc6d9c620  40015fe      182       System.Boolean  1 instance                0 _errorTokenReceived

00007ffbc6d9c620  40015ff      183       System.Boolean  1 instance                0 _bulkCopyOpperationInProgress

00007ffbc6d9c620  4001600      184       System.Boolean  1 instance                0 _bulkCopyWriteTimeout

00007ffbc86595d8  4001601       38 ...lClient.SNIPacket  0 instance 0000003ff6061b18 _sniPacket

00007ffbc86595d8  4001602       40 ...lClient.SNIPacket  0 instance 0000003f76cc7ae8 _sniAsyncAttnPacket

00007ffbc8659500  4001603       48 ....WritePacketCache  0 instance 0000003ff605d728 _writePacketCache

00007ffbc8659698  4001604       50 ...et, System.Data]]  0 instance 0000003ff605d770 _pendingWritePackets

00007ffbc6d96080  4001605       58        System.Object  0 instance 0000003ff605d7c0 _writePacketLockObject

00007ffbc6f9cf88  4001606      198 ...Services.GCHandle  1 instance 0000003ff605d6f0 _gcHandle

00007ffbc6d9f6f0  4001607      150         System.Int32  1 instance                1 _pendingCallbacks

00007ffbc6de0630  4001608      110         System.Int64  1 instance 3600000 _timeoutMilliseconds

00007ffbc6de0630  4001609      118         System.Int64  1 instance 0 _timeoutTime

00007ffbc6d9c620  400160a      185       System.Boolean  1 instance                0 _attentionSent

00007ffbc6d9c620  400160b      186       System.Boolean  1 instance                0 _attentionReceived

00007ffbc6d9c620  400160c      187       System.Boolean  1 instance                0 _attentionSending

00007ffbc6d9c620  400160d      188       System.Boolean  1 instance                0 _internalTimeout

00007ffbc8659f30  400160e       60 ...lient.LastIOTimer  0 instance 0000003ff605d860 _lastSuccessfulIOTimer

00007ffbc6d9ba28  400160f       68      System.Object[]  0 instance 0000003ff605d7d8 _securePasswords

00007ffbc6f08e38  4001610       70       System.Int32[]  0 instance 0000003ff605d808 _securePasswordOffsetsInBuffer

00007ffbc6d9c620  4001611      189       System.Boolean  1 instance                0 _cancelled

00007ffbc6d9f6f0  4001612      154         System.Int32  1 instance         12664123 _allowObjectID

00007ffbc6d9c620  4001613      18a       System.Boolean  1 instance                1 _hasOpenResult

00007ffbc860ef98  4001614       78 ...ternalTransaction  0 instance 0000000000000000 _executedUnderTransaction

00007ffbc6de0db8  4001615      120        System.UInt64  1 instance 0 _longlen

00007ffbc6de0db8  4001616      128        System.UInt64  1 instance 0 _longlenleft

00007ffbc6f08e38  4001617       80       System.Int32[]  0 instance 0000000000000000 _decimalBits

00007ffbc6e30eb0  4001618       88        System.Byte[]  0 instance 0000003c7570fa38 _bTmp

00007ffbc6d9f6f0  4001619      158         System.Int32  1 instance                0 _bTmpRead

00007ffbc702fe68  400161a       90  System.Text.Decoder  0 instance 0000000000000000 _plpdecoder

00007ffbc6d9c620  400161b      18b       System.Boolean  1 instance                0 _accumulateInfoEvents

00007ffbc865e328  400161c       98 ...or, System.Data]]  0 instance 0000000000000000 _pendingInfoEvents

00007ffbc6e30eb0  400161d       a0        System.Byte[]  0 instance 0000003ff605d828 _partialHeaderBuffer

00007ffbc6d9f6f0  400161e      15c         System.Int32  1 instance                0 _partialHeaderBytesRead

00007ffbc860f2b0  400161f       a8 ...t._SqlMetaDataSet  0 instance 0000003c77298240 _cleanupMetaData

00007ffbc865ead8  4001620       b0 ...DataSetCollection  0 instance 0000000000000000 _cleanupAltMetaDataSetArray

00007ffbc6d9f6f0  4001621      160         System.Int32  1 instance              208 _tracePasswordOffset

00007ffbc6d9f6f0  4001622      164         System.Int32  1 instance              144 _tracePasswordLength

00007ffbc6d9f6f0  4001623      168         System.Int32  1 instance              648 _traceChangePasswordOffset

00007ffbc6d9f6f0  4001624      16c         System.Int32  1 instance                0 _traceChangePasswordLength

00007ffbc6d9c620  4001625      18c       System.Boolean  1 instance                0 _receivedColMetaData

00007ffbc862b0a0  4001626      170         System.Int32  1 instance               11 _sniContext

00007ffbc6d9c620  4001627      18d       System.Boolean  1 instance                0 _bcpLock

00007ffbc862b288  4001628      1a0 ...Object+NullBitmap  1 instance 0000003ff605d6f8 _nullBitmapInfo

00007ffbc8574750  4001629       b8 ...bject, mscorlib]]  0 instance 0000000000000000 _networkPacketTaskSource

00007ffbc7010048  400162a       c0 ...m.Threading.Timer  0 instance 0000000000000000 _networkPacketTimeout

00007ffbc6d9c620  400162b      18e       System.Boolean  1 instance                1 _syncOverAsync

00007ffbc6d9c620  400162c      18f       System.Boolean  1 instance                0 _snapshotReplay

00007ffbc865c0b0  400162d       c8 ...ect+StateSnapshot  0 instance 0000000000000000 _snapshot

00007ffbc70106c0  400162e       d0 ....ExecutionContext  0 instance 0000000000000000 _executionContext

00007ffbc6d9c620  400162f      190       System.Boolean  1 instance                0 _asyncReadWithoutSnapshot

00007ffbc860cb40  4001630       d8 ...qlErrorCollection  0 instance 0000000000000000 _errors

00007ffbc860cb40  4001631       e0 ...qlErrorCollection  0 instance 0000000000000000 _warnings

00007ffbc6d96080  4001632       e8        System.Object  0 instance 0000003ff605d848 _errorAndWarningsLock

00007ffbc6d9c620  4001633      191       System.Boolean  1 instance                0 _hasErrorOrWarning

00007ffbc860cb40  4001634       f0 ...qlErrorCollection  0 instance 0000000000000000 _preAttentionErrors

00007ffbc860cb40  4001635       f8 ...qlErrorCollection  0 instance 0000000000000000 _preAttentionWarnings

00007ffbc8574750  4001636      100 ...bject, mscorlib]]  0 instance 0000000000000000 _writeCompletionSource

00007ffbc6d9f6f0  4001637      174         System.Int32  1 instance                0 _asyncWriteCount

00007ffbc6de5290  4001638      108     System.Exception  0 instance 0000000000000000 _delayedWriteAsyncCallbackException

00007ffbc6d9f6f0  4001639      178         System.Int32  1 instance                0 _readingCount

00007ffbc6d9f6f0  40015e9      a74         System.Int32  1   static            18587 _objectTypeCount

 

And Finally the _outbuff, which has the actual sproc name

 0:118> !do 0000003ff605fab8

Name:        System.Byte[]

MethodTable: 00007ffbc6e30eb0

EEClass:     00007ffbc6e30e20

Size:        8024(0x1f58) bytes

Array:       Rank 1, Number of elements 8000, Type Byte

Content:     ...S............................p.r.c._.Q.u.e.r.y.B.u.i.l.d.s.B.y.U.r.i....@.p.a.r.t.i.t.i.o.n.I.d..&...>...@.b.u.i.l.d.U.r.i.T.

Fields:

Now that you know which sproc call is leaking you can start inspecting the code to see who is making these calls, also, if you are lucky enough you might be able to find the stack trace causing the leak!