Thread Detail

Edit online

This panel provides detailed information about the activity of a selected thread or parallel task.

A parallel task is created from an originating thread to process a part of a query. Thread activity is broken down into general status and resource consumption information, and buffer manager activity.

________________ ZTDTL    VTM     O2       V610.#P SB1A 01/18/18 12:21:19   2 
> Help PF1                                                            Back PF3 
                                                                               
>       THREAD INFORMATION:  Enter a selection letter on the top line.         
                                                                               
> *-THREAD DETAIL B-LOCK COUNTS C-LOCK WAITS     D-LOCKS OWNED  E-GLOBAL LOCKS 
> F-CURRENT SQL   G-SQL COUNTS  H-DISTRIBUTED    I-BUFFER POOL  J-GROUP BP     
> K-PACKAGES      L-RES LIMIT   M-PARALLEL TASKS N-UTILITY      O-OBJECTS      
> P-CANCEL THREAD Q-DB2 CONSOLE R-DSN ACTIVITY   S-APPL TRACE   T-ENCLAVE      
> U-LONG NAMES                  W-ACCEL ACTIVITY                               
===============================================================================
>                                THREAD DETAIL                                 
 PLAN                                                                          
+ Thread:  Plan=DISTSERV  Connid=SERVER   Corrid=db2jcc_appli Authid=TS5787    
+ Dist  :  Type=DATABASE ACCESS, Luwid=GA053D54.F022.D3C2079269BC=4263         
+ Location  :  ::FFFF:10.5.61.84                                               
 act                                                                           
+ Thread Activity                         User Defined Functions               
+ -------------------------------------   -------------------------------------
+ DB2 Status          =     IN-SQL-CALL   TCB Time (SQL)      = 00:00:00.000000
+ MVS Status          =                   Wait for TCB Time   = 00:00:00.000000
+ Total Elapsed Time  = 00:00:09.846946   Elapsed Time        = 00:00:00.000000
+ CP CPU Utilization  =           00.0%   Elapsed Time (SQL)  = 00:00:00.000000
+ Total CP CPU Time   = 00:00:00.000000   SQL Events          =               0
+ SE CPU Time         = 00:00:00.000404                                        
+ Total Parallel Tasks  =             0                                         
+ Current Parallel Tasks=             0                                         
+ Thread Status         =            T                                          
+                                                                               
+ In-DB2 Times                                    Total           Current       
+ ------------------------------                  ------------    ------------  
+ Elapsed Time                                    00:00:00.007    00:00:00.000  
+ CP CPU Time                                     00:00:00.005             N/A  
+ IIP CPU Time                                    00:00:00.000             N/A  
+ Stored Procedure CPU Time                       00:00:00.000    00:00:00.000  
+ STP CP CPU Time                                 00:00:00.000             N/A  
+ STP IIP CPU Time                                00:00:00.000             N/A  
+ STP Elapsed Time Main                           00:00:00.000             N/A  
+ UDF CP CPU Time                                 00:00:00.000             N/A  
+ UDF IIP CPU Time                                00:00:00.000             N/A  
+ UDF Elapsed Time Main                           00:00:00.000             N/A  
+                                                                               
+ Stored Procedures                       Triggers                              
+ -------------------------------------   ------------------------------------- 
+ Total CPU             =  00:00:00.000   TCB not in Enclave     = 00:00:00.000 
+ Elapsed time          =  00:00:00.000   Elapsed not in Enclave = 00:00:00.000 
+ Elapsed Time (SQL)    =  00:00:00.000   TCB prior to Enclave   = 00:00:00.000 
+ Wait for TCB Time     =  00:00:00.000                                         
+ Wait Event Count      =             0                                         
+ Curr Wait TCB Time    =  00:00:00.000                                         
+                                                                               

                                                                              
+ SavePoints                                                                    
+ -------------------------------------                                         
+ Savepoint Requests    =             0                                         
+ Release Savepoints    =             0                                         
+ Rollback Savepoints   =             0                                         
+                           
+ WorkFile                                                                      
+ -------------------------------------                                         
+ Workfile Max Blocks   =        691200                                         
+ Workfile Curr Blocks  =        691200                                         
+                                                                               
+ Waits                                  Count    Total           Current       
+ --------------------------------- ----------    ------------    ------------  
+ Synchronous I/O Wait                       4    00:00:00.001    00:00:00.000  
+ Asynchronous Read I/O Wait              5752    00:00:05.189    00:00:00.000  
+ Asynchronous Write I/O Wait              423    00:00:00.474    00:00:00.000  
+ Local Lock/Latch Wait                      0    00:00:00.000    00:00:00.000  
+ Page Latch Wait                            0    00:00:00.000    00:00:00.000  
+ Drain Lock Wait                            0    00:00:00.000    00:00:00.000  
+ Drain of Claims Wait                       0    00:00:00.000    00:00:00.000  
+ Archive Log Mode(Quiesce) Wait             0    00:00:00.000    00:00:00.000  
+ Archive Read from Tape Wait                0    00:00:00.000    00:00:00.000  
+ Switch to Open/Close Wait                  0    00:00:00.000    00:00:00.000  
+ Switch to SYSLGRNG Service Wait            0    00:00:00.000    00:00:00.000  
+ Switch to DMS Waits                        0    00:00:00.000    00:00:00.000  
+ Other Service Waits                        0    00:00:00.000    00:00:00.000  
+ Force at Commit Waits                      0    00:00:00.000    00:00:00.000  
+ Log Write I/O Wait                         0    00:00:00.000    00:00:00.000  
+ Sync EX Unit Sw-com/abort/dealloc          0    00:00:00.000    00:00:00.000  
+ LOB Materialization                        0    00:00:00.000    00:00:00.000  
+ Latch Contention Wait                    461    00:00:00.040    00:00:00.000  
+ Autonomous Proc Wait                       0    00:00:00.000    00:00:00.000  
+ Parallel Query Sync Wait                   0    00:00:00.000    00:00:00.000  
+ Asynch IXLCACHE/IXLFCOMP                   0    00:00:00.000    00:00:00.000  
+ Fast Insert Pipe Wait                      0    00:00:00.000    00:00:00.000  
+ Accelerator Wait                           0    00:00:00.000    00:00:00.000  
+ ------------------------------------------------------------                  
 Total Class 3 Wait Time                 6640    00:00:05.705                 
==============================================================================

Highlighting

The following table shows the fields that might be highlighted in the panel above to indicate that an exception that is related to this field exceeded its threshold value:
Table 1. Highlighted fields in Thread Detail panel

This table shows the fields and the exceptions these fields are related to. It also shows the reason for the corresponding exception. For the field Plan, more than one exception code is available.
Field Exception Reason
Plan ARCM Backout requires an archive tape log mount.
ETIM This thread has reached the Elapsed Time threshold value.
GETP The Getpage to Read I/O ratio indicates poor read efficiency.
INDB The thread is indoubt and terminated.
PREF The thread Sequential Prefetch rate is high.
RIO The synchronous Read I/O rate is high.
PGUP The rate for system page updates is high.
Total Elapsed Time ETIM This thread reached the Elapsed Time threshold value.
CPU Utilization TCPU The CPU utilization associated with the thread is high.
Current® Drain Lock Wait WDLK The thread reached drain lock wait threshold.
Current Drain of Claims Wait WCLM The thread reached wait for drain of claims threshold.
Current Service Task Wait WSRV The thread reached Db2® service wait threshold.
Current Archive Log Mode (Quiesce) Wait WLGQ The thread reached Archive Log Mode (Quiesce) wait threshold.
Current Stored Procedure Schedule Wait WSPS The thread reached stored procedure schedule wait threshold.
Total elapsed time IDBT In-Db2 Times - Total elapsed time.
Total CP CPU wait IDBC In Db2-Times - Total CP CPU wait.
Current global parent L-lock wait WGLK The thread reached the global lock wait threshold.

Navigation

You can scroll through the information using F7 and F8.

For additional information about
  • related topics, select one of the options on the top of the panel.
  • other topics, use the PF keys.

Fields

If the accounting trace classes are not active, the fields show N/A (not applicable) instead of a value.

Thread identifier: This information identifies the thread to which the information in this panel applies.
Plan
The Db2 plan name of the active thread.
Connid
The Db2 connection identifier of the active thread.
Corrid
The Db2 correlation identifier of the active thread. If the correlation is not set, N/A is displayed.
Authid
The Db2 authorization identifier of the active thread.
Attach
Depending on the type of connection, the appropriate information is displayed.
Attach information is displayed only if the thread is a distributed allied thread (not for distributed database access threads).
Connection Type
Batch
The MVS™ jobname and ASID.
Note: For threads from remote Db2, the MVS job name is N/A.
CICS®
The CICS jobname, task name, task number, terminal ID, and thread type. The thread type is:
Pool
The thread in use is a pool thread.
Entry
The thread in use is a nonprotected entry thread.
Prot
The thread in use is a protected thread. Protected threads are defined in an RCT entry definition using the THRDS operand.
IMS™
The IMS region number, transaction name, region name, and terminal ID (LTERM).
RRSAF
The MVS job name and ASID.
Note: For threads from remote Db2, the MVS job name is N/A.
System
The originating Db2 job name and the resource manager that is the source of the thread. An additional line below the Attach line identifies the user thread, if any, being served by the system thread.
TSO
The TSO user ID and region ASID.
Utility
No additional information.
Db2
The Db2 subsystem identifier.
MVS
The MVS system identifier.
ORIGAUTH
The original (primary) Db2 authorization identifier of the thread. This field displays only when the original identifier is different from the Authid.
Package identifier: This information identifies the package to which the information in this panel applies.
Package
The Db2 package name of the active thread. Up to 18 characters of the package name are returned.
Collection
The package collection identifier. This field is displayed only if a package is being used.
Distributed thread identifier: The following fields are displayed if the thread has a distributed relationship with a remote Db2 subsystem.
Type
The distributed thread type.
Distributed Allied
A requesting thread; one that has issued an SQL call to a remote Db2 location.
Database Access
A responding thread; one that is serving a remote Db2 location by responding to an SQL call.
Db2=
The Db2 subsystem ID, indicating the member of the data sharing group of this thread.
Luwid
This value consists of two parts: the logical unit of work ID (luw-id) and a token. The token can be used in place of the luw-id in any Db2 command that accepts luw-id as input. Format:
luw-id=token

The luw-id consists of the network name, the originating VTAM® LUNAME, and a unique identifier (separated by periods). Thus, the Luwid field displays data like in the following example:

USCACO01.O2D22A.A1FE8E04B9D4=8
System
The originating Db2 job name and the resource manager that is the source of the thread. An additional line below the Attach line identifies the user thread, if any, being served by the system thread.
Thread Activity:
Db2 Status
The Db2 status.
MVS Status
The current MVS status of the thread:
Asid Notdisp
The address space in which the active task is not available for dispatch.
Db2 I/O Wait
The thread is waiting for the completion of Db2 database I/O.
Logical Swap
The address space is currently logically swapped out.
Swapped Out
The memory is physically swapped out.
Using CPU
The thread is currently using CPU cycles.
Wait-Dispatch
The task is waiting on the active CPU dispatching queue. It is available for use, but is not yet running on a processor.
WAIT-MISC
The thread is waiting for some other reason and is not on the available dispatch queue.
Note: If the panel displays a distributed database access thread, this field is blank.
Total Elapsed Time
The total elapsed time for the thread, in the format hh:mm:ss.tht. Elapsed time is the time which has elapsed since thread creation or Db2 signon.
CP CPU Utilization
The central processor CPU rate (percent) associated with the thread.

For non-CICS threads, this is the central processor CPU rate of the address space from which the thread originates. For CICS threads, this is the central processor CPU rate attributable to the thread originating from the CICS connection.

Total CP CPU Time
The total central processor CPU time accumulated for the thread. This value includes only MVS TCB time. SRB time is not included.
SE CPU Time
The accumulated CPU time consumed while executing on an IBM® specialty engine.
Total Parallel Tasks
The total number of parallel tasks that were created on behalf of this thread.
Current Parallel Tasks
The number of parallel tasks currently executing. To see information about these tasks, select option M-PARALLEL TASKS.
Thread Status
Valid values:
AC
Execute in accelerator
AT
Process autonomous procedure
D
Termination due to allied task's termination
DA
DBaccess thread slot is available for new connection
DI
Disconnected, no TCB associated with the Db2 thread. (Available for reuse.)
N
In IDENTIFY or SIGNON status
ND
IN IDENTIFY or SIGNON status with no TCB associated
PT
Parallel task thread
QD
Queued for termination due to allied task's termination
QT
CREATE THREAD request is queued
R2
Type2 inactive thread waiting for agent to become available
RA
Active distributed thread performing remote access
RK
Distributed thread invokes Kerberos services
RN
Distributed thread waits for system conversation service task
RQ
Distributed thread waits for dbaccess agent, due to MAXDBAT or DSN_PROFILE_ATTRIBUTES_TABLE
RX
Distributed thread executes XA transaction
SP
In stored procedure
SW
Wait for a stored procedure to be scheduled
T
Non-distributed allied thread
TD
An allied thread is not associated with TCB
TN
An allied thread is waiting for system conversation service task
TR
An allied thread is active
The following QW0148ST is supported in DB2 V12 and higher:
RP
Denotes an active, high performance DBAT waiting for the next transaction from its remote connection and the DBAT is not a candidate for idle thread detection and termination based on IDTHTOIN subsystem parameter.
RD
Denotes an active, KeepDynamic-refreshable DBAT waiting for the next transaction from its remote connection and the DBAT is not a candidate for idle thread detection and termination based on IDTHTOIN subsystem parameter.
RH
Denotes an active DBAT waiting for the next transaction from its remote connection but it is being kept active with its connection due to resources being held past a commit/rollback. A DBAT with this status is a candidate for idle thread detection and termination based on IDTHTOIN subsystem parameter. The possible resources are:
  • open, WITH HOLD cursor(s)
  • allocated declared global temporary table(s)
  • held lob locators
  • commit performed within a stored procedure which requires a two-phase commit/rollback from the client connection
  • active KEEPDYNAMIC package(s) but the client did not request KeepDynamic refresh
User-Defined Functions:
TCB Time (SQL)
The accumulated CPU time consumed executing user-defined functions. This time does not include CPU time consumed on an IBM specialty engine. It consists of following parts:
  • The accumulated CPU time consumed in Db2 when processing SQL statements that were issued by UDFs in a Db2 stored procedure or WLM address space. This time also includes the Db2 time required to connect or disconnect the UDF task. It is only calculated if accounting class 2 is active.
  • The accumulated CPU time consumed executing user-defined functions on the main application execution unit. This time represents class 1 and class 2 time, because these UDFs run entirely within Db2.
Wait for TCB Time
Total elapsed time spent waiting for an available TCB before the user-defined function could be scheduled.
Elapsed Time
Total elapsed time spent in user-defined functions, including time executing SQL statements.
Elapsed Time (SQL)
Total elapsed time spent in user-defined functions executing SQL statements.
SQL Events
Number of SQL entry/exit events performed by user-defined functions.

In-Db2 Times

Elapsed Time (Total)

The accumulated CPU time consumed executing user-defined functions. This time does not include CPU consumed on an IBM specialty engine. It consists of following parts:

The accumulated CPU time used to satisfy UDF requests processed in a Db2 stored procedure or WLM address space. This time is only calculated if accounting class 1 is active.

The accumulated CPU time consumed executing user-defined functions on the main application execution unit. This time represents class 1 and class 2 time, because these UDFs run entirely within Db2.

Elapsed Time (Current)

The total amount of time spent executing the currently active SQL statement. It is only calculated if monitor class 9 is activated.

CP CPU Time (Total)
The class 2 CPU time (in Db2). It indicates:
  • The class 2 CPU time for the allied agent. This includes the accumulated class 2 TCB time for processing any stored procedures, user-defined functions, and triggers.
  • The accumulated CPU time for processing parallel tasks. This is valid for query CP parallelism, sysplex query parallelism, and parallel tasks generated by utilities. Only CPU times of parallel tasks, running on the same member of the sysplex group as the originating task, are included. This CPU time does not include time that is consumed on an IBM specialty engine.
CP CPU Time (Current)

CPU time consumed for execution of the SQL statement. This value is not available for SQL statements that run under an SRB. Therefore, this value does not include time that is consumed on an IBM specialty engine. It is only calculated if monitor class 9 is activated.

SE CPU Time (Total)

The accumulated and consumed class 2 time on an IBM specialty engine (SE) that consists of times for non-nested, stored procedures, user-defined functions, triggers, and parallel tasks.

SE CPU Time (Current)

The total SE CPU time used by the currently active SQL statement. The value is always zero for database access threads.

Stored Procedure CPU Time (Total)

The accumulated CPU time that is used for executing stored procedure requests on the main application execution unit. This time does not include the time that is consumed on an IBM specialty engine. As these stored procedures run entirely in Db2, this time represents class 1 and class 2 time.

UDF CP CPU Time (Total)

Accumulated CPU time consumed executing user defined functions on the main application execution unit. This time does not include CPU consumed on an IBM specialty engine. Because these UDFs run entirely within Db2, this time represents class 1 and class 2 time. No current value will be provided.

UDF IIP CPU Time (Total)

Accumulated CPU time consumed executing user defined functions on the main application execution unit on an IBM specialty engine. Because these UDFs run entirely within Db2, this time represents class 1 and class 2 time. No current value will be provided.

UDF Elapsed Time Main (Total)

The accumulated CPU time consumed executing user-defined functions. This time does not include CPU consumed on an IBM specialty engine. It consists of following parts:

  • The accumulated CPU time used to satisfy UDF requests processed in a Db2 stored procedure or WLM address space. This time is only calculated if accounting class 1 is active.
  • The accumulated CPU time consumed executing user-defined functions on the main application execution unit. This time represents class 1 and class 2 time, because these UDFs run entirely within Db2.
Stored Procedures:
Total CPU
The CPU time (TCB time) spent in Db2 processing SQL statements issued by stored procedures for this thread. This is an accumulated and consumed time for stored procedures that consists of the following information:
  • The CPU time accumulated in Db2 for processing SQL statements issued by stored procedures processed in a Db2 stored procedure or WLM address space. This time is only calculated if accounting class 2 is active
  • In-Db2 time needed to connect and disconnect the SP task for non-SQL procedure stored procedures
  • SQL procedure times are included in this time if the SQL procedure was called on a nested task and was not invoked by the main application execution unit
  • CPU time that is consumed when running stored procedure requests on the main application execution unit. This time does not include the CPU time consumed on an IBM specialty engine.
Elapsed Time
Total elapsed time spent in stored procedures including time executing SQL statements. This is an accumulated and consumed time for stored procedures that consists of the following parts:
  • The CPU time accumulated in Db2 for processing SQL CALL statements in the stored procedures or WLM address space. This time is only calculated if accounting class 1 is active.
  • The accumulated CPU time consumed when running stored procedure requests on the main application execution unit. This time does not include CPU time consumed on an IBM specialty engine. As these stored procedures run entirely within Db2, this time represents class 1 and class 2 time.
Elapsed Time (SQL)
Total elapsed time spent for stored procedures executing SQL statements.
Wait for TCB Time
The total time waiting for an available TCB to schedule a stored procedure.
Wait Event Count
The number of wait trace events processed for an available TCB that are needed in order to schedule a stored procedure.
Curr Wait TCB Time
The current time waiting for an available TCB to schedule a stored procedure.
Triggers:
Trigger CPU Time
The accumulated CPU time consumed while executing under the control of triggers. For triggers there is no distinction between class 1 and class 2 CPU time. All processing controlled by a trigger is within Db2.
Elapsed not in Enclave
The accumulated elapsed time used when executing under the control of a trigger. This does not include the time used while in user-defined function or stored procedures that are called from the trigger not under an enclave.
TCB prior to Enclave
The accumulated TCB time consumed before enclave creation time.
SavePoints:
Savepoint Requests
The number of savepoints set.
Release Savepoints
The number of savepoints deleted.
Rollback Savepoints
The number of rollback-to-savepoint requests issued.
WorkFile:
Workfile Max Blocks
Maximum number of workfile blocks being used by this agent at any given point in time (traditional workfile use, DGTT and DGTT indexes). Db2 12 and later.
Workfile Curr Blocks
Current number of workfile blocks being used by this agent (traditional workfile use, DGTT and DGTT indexes). Db2 12 and later.
In-Db2 Times: In-Db2 times require an Accounting trace class 2. If this trace was not active, N/A is displayed.
Elapsed Time (Total)
The total In-Db2 elapsed time for the thread, in the format hh:mm:ss.tht.
Elapsed Time (Current)
The total time spent executing the currently active SQL statement.
CP CPU Time (Total)
The total In-Db2 central processor CPU time for the thread. This includes MVS TCB time only. SRB time is not included.
CP CPU Time (Current)
The total central processor CPU time used by the currently active SQL statement, in the format hh:mm:ss.tht. The value is always zero for database access threads.
IIP CPU Time (Total)
The total In-Db2 SE (Specialty Engine) CPU time for the thread.
IIP CPU Time (Current)
The total SE (Specialty Engine) CPU time used by the currently active SQL statement in seconds. The value is always zero for database access threads.
Stored Procedure CPU Time (Total)
The CPU time (TCB time) spent in Db2 processing SQL statements issued by Db2 stored procedures for this thread.
Stored Procedure CPU Time (Current)
The CPU time (TCB time) spent in Db2 processing SQL statements issued by Db2 stored procedure that is currently active.
UDF CP CPU Time (Total)
The CPU time spent in Db2 processing SQL statements issued by user defined functions for this thread. This time represents central processor time only and does not include SE (Specialty Engine) time.
UDF IIP CPU Time (Total)
The amount of SE (Specialty Engine) CPU time spent in Db2 processing SQL statements issued from user defined functions for this thread.
UDF Elapsed Time Main (Total)
The elapsed time by the user defined functions for this thread in the format hh:mm:ss.tht.
Waits (Class 3): Wait times require an Accounting trace class 3. If this trace is not active, N/A is displayed. For each field described below the following statistics are provided:
  • Count is the total number of waits.
  • Total is the total wait time that has elapsed.
  • Current is the elapsed time waiting for the current event to complete.
Synchronous I/O Wait
Waits for synchronous I/O reads or writes.
Asynchronous Read I/O Wait
Waits for Read I/O performed under another thread (for example, list or Sequential Prefetch).
Asynchronous Write I/O Wait
Waits for Write I/O performed under another thread (for example, deferred writes).
Local Lock/Latch Wait
Waits for locks or latches.
Page Latch Wait
Waits for page latch.
Drain Lock Wait
Waits to acquire drain lock.
Drain of Claims Wait
Waits for claims to be released after acquiring drain lock.
Archive Log Mode (Quiesce) Wait
Wait for ARCHIVE LOG MODE(QUIESCE) command to complete.
Archive Read from Tape Wait
Waits for read of archive log from tape.
Switch to Open/Close Wait
Wait for switches to the OPEN/CLOSE service.
Switch to SYSLGRNG Service Wait
Wait for switches to the SYSLGRNG recording service.
Switch to DMS Waits
Wait for switches to the database-managed space (DMS).
Other Service Waits
Wait for switches to other Db2 service tasks.
Force at Commit Waits
Wait for force-at-commit Db2 service tasks.
Log Write I/O Wait
Waits due to Log write I/O.
Sync EX Unit Sw-com/abort/dealloc
Waits due to synchronous execution switch for Db2 commit, abort, or deallocation processing.
LOB Materialization
Waits for TCP/IP LOB and XML materialization.
Latch Contention Wait
Waits due to page latch contention.
Autonomous STP Wait (QWAC_AT_WAIT QWAC_AT_COUNT)
The amount of waits that are due to autonomous procedures.
This applies to Db2 11 and higher.
Parallel Query Sync Wait (QPAC_PQS_WAIT QPAC_PQS_COUNT)
The amount of waits after parallel query processing suspended waiting for parent/child to be synchronized.
This applies to Db2 11 and higher.
Asynch IXLCACHE/IXLFCOMP (QWAXIXLT)
The accumulated wait time for IXLCACHE and IXLFCOMP requests.
Fast Insert Pipe Wait
The accumulated wait time for a pipe wait. Db2 12 and later.
Accelerator Wait (QWACAACW QPACAACC)
The accumulated wait time for requests to an accelerator. Db2 11 and later.
Total Class 3 Wait Time
The total class 3 wait time.
For Data Sharing Group members, the following waits are also displayed:
Global Child L-Locks (QWACAWTK QWACARNK)
Waits because of global contention for child L-locks.
Global Other L-Locks (QWACAWTM QWACARNM)
Waits because of global contention for other L-locks.
Global Pageset/Partition P-Locks (QWACAWTN QWACARNN)
Waits because of global contention for Pageset/Partition P-locks.
Global Page P-Locks (QWACAQTO QWACARNO)
Waits because of global contention for Page P-locks.
Global Other P-Locks (QWACAQTQ QWACARNQ)
Waits because of global contention for other P-locks.