Thread Debugging Support | HP gnu source-level debugger 5992-4701

set heap-check high-mem-count	Stops when brk() value has moved X_number
X_number	of times.
Limitations:

•This feature assumes that an application has a deterministic memory allocation pattern from one run to another.

•The high_mem feature is not supported in batch mode debugging.

14.11Thread Debugging Support

HP WDB provides thread-debugging support for kernel, user, and MxN threads. You can exclusively disable or enable specific thread execution. Advanced thread debugging support in HP WDB enables you to view information on pthread primitives and detect certain thread-related conditions.

NOTE: WDB supports pthread parallelism, but it does not support compiler-generated parallelism such as parallelism with directives.

14.11.1Support for Enabling and Disabling Specific Threads

When you suspect that a specific thread is causing a problem while debugging a multi- threaded application, you can suspend the execution of other threads in the application and debug the doubtful thread exclusively. HP WDB 3.2 and later versions provide the following commands to disable and enable specific thread execution:

thread disable This command prevents the specified threads from running until they are enabled again using the thread enable command.

thread enable This command enables the specified thread to run when you issue the continue or step command. By default, all threads are in the enabled state. You can use the thread enable command to reactivate a disabled thread.

Consider the following example:

(gdb) info threadsystem thread 4189 0x7f666da8

in __pthread_create_system+0x3d8 () from /usr/lib/libpthread.1

2 system thread 4188 worker (wptr=0x40004640 ") at quicksort.c:135

1 system thread 4184 0x7f66f728 in _lwp_create+0x10 () from /usr/lib/libpthread.1

To disable a thread, execute the following command:

(gdb) thread disable 1

warning: ATTENTION!! Disabling threads may result in deadlocks in the program.Disabling thread 1

To enable a thread, execute the following command:

(gdb) thread enable 1 Enabling thread 1

14.11 Thread Debugging Support 181

Image 181

HP gnu source-level debugger 5992-4701 manual Thread Debugging Support, Support for Enabling and Disabling Specific Threads

Contents

Debugging with GDB Manual Page Table of Contents Print settings Value history Continuing and stepping SignalsBreakpoints Stack frames Examining the Symbol Table Specifying a Debugging Target Scramble previous memory contents at malloc/free calls Stop when freeing unallocated or deallocated blocksBatch Mode Commands for heap profiling Support for the dumpcore command Support for the info target CommandEnhancements to the dumpcore command Example Illustrating Execution Path Recovery Support for steplast command for C and C++ Command for evaluating the address of an expressionDebugging the application using GDB under Aries Detecting memory leaks using GDB under Aries HP-UX Terminal User Interface Setting Command History Feature in GDB 281 17.4 Miscellaneous commands 265 16.3User-defined commands 287 18.2 Command files 289 Commands for controlled output 290 22.2 How to report bugs 361 20.7 Errors 302 20.820.9 Invalidation notices 303 304 List of Tables List of Examples Free Software Summary of GDBContributors to GDB Page Contributors to GDB Page Sample GDB Session Let us use GDB to try to see what is going onLoading the Executable Setting Breakpoints Setting Display widthHere we describe how to set a breakpoint Running the executable under GDB Examining the Stack Stepping into a subroutinePrinting Variable Values Listing Source Code Setting Variable Values During a Session Gdb c Continuing Definebaz,defnQUOTEfooUNQUOTE Baz Page Invoking GDB Getting In and Out of GDB Files Choosing files Choosing modes Processed. See Command files Line number in a standard, recognizable fashion each GNU Emacs sets this option when it runs GDB as aTime a stack frame is displayed which includes each Like two `\032 characters, followed by the file name Emacs Redirecting WDB input and output to a file Quitting GDBInterface Shell commands Page Command syntax GDB CommandsCommand completion GDB sounds bell press TAB again, to see Getting help Short list of named classes of commandsHelp , h Results Apropos reloadComplete This is intended for use by GNU Emacs Getting help Page Compiling for debugging Running Programs Under GDBStarting your program Arguments, so that you may use normal Your program. SeeProgram Environment See Arguments To Your ProgramDirectory Program Environment Arguments To Your ProgramProgram. See Program Input and Output Display the list of search paths for executables For example, this commandPath environment variable Do not supply varname, print the names Program Input and Output Working directory Debugging a Running Process Killing the child process Debugging programs with multiple threads New process 35 thread Thread apply command allows you to Here are commands to get more information about threadsWith the command argument threadno Display a summary of all threads currently Debugging programs with multiple processes Unimpeded. This is the default New process. The mode can beSet the debugger response to a program call Fork. The child process runs Breakpoints Stopping and Continuing Setting breakpoints Breakpoints See Break conditions page 59, for more Catchpoint BreakpointWhether Breakpoint is Enabled When hitMarked to be Breakpoints are Setting catchpoints Is currently only available for HP-UX Call to vfork. This is currently onlyUnloading of any dynamically loaded Shared library, or the unloading Disabling breakpoints Deleting breakpointsSelecting a frame page 73 . When Break conditions No symbol foo in current context Breakpoint, GDB prints an error messageStops your program only if the value Use condition, GDB checks expression Breakpoint command lists Breakpoint menus Cannot insert breakpoints Conditions Continuing and stepping Function Setting breakpoints page 52. This form of the command Stops. See Automatic display Signals Info handle is an alias for info signals Stopping and starting multi-thread programs Stopping and Continuing Stack frames Examining the Stack Stacks Without frames Commands for Examining the StackBacktraces Selecting a frame When used without any argument, this command does not Have existed longer. n defaults to oneWith an argument, this command is used to select a stack Information about a frame Setting catchpoints Page Printing source lines Examining Source FilesList Show listsize Searching source files Specifying source directories Show directories Source and machine codeContains Disassemble or x/i commands Set disassembly-flavorSelect the instruction set to use when Disassembling the program viaPage Examining Data Following forms of print command are supportedExpressions To See Artificial arrays page 85, for more information Program variables Where it is defined. See Program variablesType addr Normally supposed to reside at addr Artificial arrays You can print the contents of array with Output formats Examining memory Machine instruction. The default isPrint, s null-terminated string, or Time you use either x or print However, the count n must come first wx4 does not work For fmt specifying only a display format and not a size or Automatic displaySee Output formats For fmt i or s, or including a unit-size or a number Print settings File name and line number of a symbol A symbol. This is the defaultSymbolic form of an address Address Strings. When GDB starts, this limit is set to Default is offSetting number-of-elementsto zero Short strings. The default is off Show which format GDB is using to print This is the default formatPrint using only seven-bit characters if this Default Default is on These settings are of interest when debugging C++ programsShow whether C++ names in assembly listings Would print Value history Convenience variables Format in which the data was printed Command, in which case it is a pointer to the type of $$exitcode Program being debugged terminates Info registers Info all-registers Info registers regname RegistersOr print the instruction to be executed next with Or add four to the stack pointer3 with3with Floating point hardware Printing Floating Point ValuesTo get the bit pattern, try the following macro This is what the macro produces 100 Switching between source languages Using GDB with Different LanguagesList of filename extensions and languages Cpp Not skip over function prologues when stepping Setting the working languageHaving GDB infer the source language Files Type and range checking Displaying the languageAn overview of type checking An overview of range checking Supported languages C++ Non-zero for true Expressions is 0 for false and non-zero for trueLeft shift, and right shift. Defined on integral types Types and pointer types Double colons also represent the GDB scope operator see Class typesExpressions page 83. Same precedence as , above C++ constants GDB expression handling can interpret most C++ expressions 1.3 C++ expressions Printing the variable or class returns C++ defaultsC++ type and range checks GDB and C GDB features for C++Breakpoint menus See Breakpoint menus Fortran types FortranFortran types supported Less than or equal to Less thanGreater than Greater than or equal to Commonblockname Fortran special issuesBlock Examining the Symbol Table As with whatis, using ptype without an Two commands give this outputSymbols will be read when needed For example, for this variable declaration Replace symbol definitions Allow GDB to reload the symbols forDo not replace symbol Once. This is the default Is in another source file. The default is on SettingTell GDB to resolve opaque types. An opaque Class, or union―for example, struct Assignment to variables Altering Execution Stores the value 4 into that memory location Continuing at a different address You can use the following command to return from a function Giving your program a signalReturning from a function Patching programs Calling program functionsReturn , return Is used as the return value from the function value Patching programs 124 GDB Files Commands to specify files See Optional warnings and messages GDB has the entire symbol table available Option with any of the commands that loadWrite the symbols for your program into a Map in symbol information from this auxiliary Section To display or set the threshold, use the commands Symbols were loaded. Both the commands listIf threshold is nonzero, symbols from all New library has been loaded, until the symbol Searching the default system directories Names where the desired shared libraries reside. GDBSpecifying shared library locations Megabytes Verbose on. See Optional warnings Errors reading symbol filesMessages Is the symbol type of the uncomprehended Symbol scope block as starting on the previousGDB circumvents the error by ignoring this Debug your program, though certain symbols Specifying a Debugging Target Commands for managing targetsActive targets See Commands to specify files Choosing target byte order Instruct GDB to assume the target is little-endian Instruct GDB to assume the target is big-endianExecutable Display GDBs current idea of the target byte order Summary of HP Enhancements to GDB HP-UX Configuration-Specific Information Support for setting breakpoints using shared library name Implementation of ask mode for set follow-fork-mode Command watchtarget Linker Dependencies HP-UX dependenciesDependent Standard Library Routines for Run Time Checking Getpid Close Srand Strchr Abort Unlink Atoi Supported Platforms and Modes Support for Alternate root HP-UX targetsWDB Location GDB location Librtc.sl location $WDBROOT/bin Opt/langtools/ n/a Specifying object file directoriesNone Bin $WDBROOT/bin Fix and continue debugging Fix and Continue restrictions Fix and Continue compiler dependencies Using Fix and Continue Compile the program Example Fix and Continue sessionRun the program Gdb run Gdb b mainGdb edit Make the necessary changes. In this case, add return total Inline Debugging in HP 9000 Systems Inline SupportGdb q Following options available for the set inline-debugcommand Breakpoint info frame disassemblyInline Debugging in Integrity Systems Step next list backtrace frame n info locals info args Debugging Inline Functions in Integrity Systems Limitations Debugging Macros Info frame disassemblyViewing and Evaluating Macro Definitions Evaluating Macros Compiler Options to Enable Macro DebuggingDebug=none Examples for Macro Debugging HP-UX Configuration-Specific Information Debugging Memory Problems Memory debugging restrictions When to suspect a memory leakMemory Debugging Methodologies Debugging Memory in Interactive Mode This command are ignored from report. If Displays all current settings for memoryHeap growth. The default value is 100. Every Command discards the data existing in the file Debugging Memory Problems Have occurred and WDB reports the problem Debugging when the string option is set forSpecific pattern when it is allocated or Such as attempting to access space that is freed If the user specifies a value less than 16 for Use the info command to show list of memory leaksNumber of bytes, the debugger ignores it User-specified value Setting Configuration Options for Batch Mode Debugging Memory in Batch ModeGdb info leak Sets the number of frames to be printed for leak context Framecount=noframes or set heap-check frame-count noframes For 64 bit IPF applications For 32 bit IPF applicationsFor 64 bit PA applications For 64-bit IPF applications Ldpreload Environment variable setting for Batch mode debugging Aborts execution when out of memory Aborts execution when heap objectsLog file for batch mode must be Stderr error message goes to stderr Example for Batch Mode RTC Complete one of the following steps Preload the librtc library as follows Rtcconfig file should contain entries such as the followingRun the program as follows For 32 bit PA applications Run the program Start a debugging session as follows Configuring memory debugging settingsSpecifying the stack depth Specifying minimum leak size Scenarios in memory debugging Stop when freeing unallocated or deallocated blocksFor example, if you use Specifying minimum block size Interactive debugging mode set heap-check scramble on off Scramble previous memory contents at malloc/free callsSyntax Detect dangling pointers and dangling blocks Detect in-block corruption of freed blocks Off Memory Debugging Commands in Interactive and Batch Mode Point you use the info heap command Commands for heap profilingHeap Profiling As the start of the heap, end of the heap, heap Set a breakpoint This example shows how to use this feature on HP-UX Changes for a given run Commands to track the change in data segment value Support for Enabling and Disabling Specific Threads Thread Debugging Support Advanced Thread Debugging Support Backtrace Support for Thread Debugging Pre-requisites for Advanced Thread Debugging Enabling and Disabling Advanced Thread Debugging Features Unlock-not-own onoff The set thread-check unlock-not-own Onoff command checks if an applicationMixed-sched-policy onoff The set thread-check Cv-multiple-mxs onoff The set thread-check cv-multiple-mxs User and prints a warning message when this This returns an Einval error toCommand checks if any thread has terminated Different mutexes. The debugger transfers Command checks if a thread has terminated When this condition is detected. This situationException or a cancel without joining or Created with the detach attribute. When an Is provided, the command displays extended Provided, the command displays extendedCondvar-id is provided, the command displays Rwlock-id is provided, the command displays For 64-bit PA applications Thread Debugging in Batch Mode For 64 bit IPF applications, set Pre-requisites for Batch mode of Thread DebuggingFor 64-bit PA applications, set Set the environment variable Batchrtc to on as And/Or Opt/langtools/lib/hpux64/librtc.so Where Pid is the process id Thread Debugging in +check ModeLimitations in Batch mode of thread debugging Issue Where pid is the process identifierDebugging MPI Programs Serial mode for set follow-fork-mode Ask mode for set follow-fork-modeSupport for showing unwind info Debugger response to a program call to fork or vfork is ask Printing CFM and PFS registers Command to Search for a Pattern in the Memory Address Space Specifies the length of the memory address range. This Parameter is mandatory when end-addressis notString value. The character pattern must be enclosed Within double quotes. This parameter is mandatory Example 14-1 Sample Output for the find command Using the /size-charparameter Using the /max-countparameterStr0 Specifies the starting address Specifies the pattern expr1 Generating core files with packcore /unpackcore/getcore Debugging Core Files Support for the info target Command When starting from the HP WDB command line Support for the dumpcore commandWhen starting from the shell prompt Enhancements to the dumpcore command Support for display of run time type information When starting from shell promptInfo rtti address Sample Output Info global-exec-path summary Info exec-path summaryExec-path updownpathindex aliased to ep Sample Program Example Illustrating Execution Path RecoverySample Debugging Session Command to Unwind Beyond 10000 Frames Invoking GDB Before a Program Aborts Aborting a Command Line Call Enhanced support for watchpoints and breakpoints Instruction Level SteppingDeferred watchpoints Hardware watchpoints Support for template breakpoints Support for procedural breakpointsRbp Rdp Debugging support for shared libraries Using shared library as main program Using catch load Setting Deferred Breakpoints in Shared LibraryPrivately mapping shared libraries Opt/langtools/bin/pxdb -s on executable-name Selectively Mapping Shared Libraries As Private Enhancement to the info shared Command Setting breakpoints in shared libraryDebugging support for Decimal Floating Point data type Printing Decimal Floating point data types Printing NaT Registers Following are sample commands to print NaT registersHandling Decimal Floating Point Data types Evaluating Decimal Floating Point data types Arithmetic Operations Assignment of Decimal floating point value to variableComparison Operations Printing type of Decimal Floating Point variable Support for Binary Floating Point constants f, l Additional Support for binary floating point data typeThis prints the binary floating point value as oat This prints the binary floating point value as double Language support Java Stack Unwind FeaturesEnhanced Java Debugging Support Gdb help java Gdb Subcommands for Java VM Debugging Java and native stack frames Frame command of GDB has been enhanced to interpret a JavaInfo frame Stack frame Java corefile debugging support Java attach mode debugging support Syntax Enhanced support for C++ templates Support for Complex variables in HP C Support for fpreg data type on IPFSupport for debugging namespaces Viewing Wide Character Strings Command for evaluating the address of an expressionThis is equivalent to executing Support for dumping array in an Ascii file Support for output logging Support for Fortran array slices Support for steplast command for C and C++Displaying enumerators Support for debugging typedefs Getting information from a non-debug executable Break Call Clear Disassem List Debugging optimized codeBreak Call Cond Jump Return Print Set var Watch Whatis HP-UX Configuration-Specific Information 14.29.1.1 +O0 and +O1 Debugging Optimized Code at Various Optimization Levels14.29.1.2 +O2/+O3/+O4/-ipo Debugging with Aries Following limitations apply when debugging optimized code+O2 or -O Limitations of GDB Support under Aries Debugging the application using GDB under Aries Attaching GDB to an already running emulated process Detecting memory leaks using GDB under Aries Starting and stopping Visual Interface for WDB Visual Interface for WDB Visual Interface for WDB GUI display Navigating the Visual Interface for WDB display Specifying foreground and background colors Using the X-window graphical interface Changing the size of the source or debugger pane Using the TUI modeFor dterm, use the following Editing the command line and command-line history Using commands to browse through source filesSaving the contents of a debugging session to a file Loading source files GNU GDB Logging Commands Support for XDB commandsSupport for command line calls in a stripped executable Stop in/at dbx commands For 32-bit applications Execute the chatr -B immediate executable command Support for debugging stripped binaries Command line calls to non-stripped libraryFor 64-bit applications Printing of locals and globals in a stripped module Linux support Displaying the current block scope informationSyntax 242 HP-UX Terminal User Interface Invoke the debugger using a command like the followingStarting the TUI Main Screen Layouts Automatically running a program at startup Disassembly pane appears when you issue the command Disassembly paneSource pane Pane looks like this Disassembly/Register pane Source/Disassembly paneSource/Disassembly pane appears when you issue the command Source/Register pane Source/Register pane appears when you issue the command Toggle split-screen mode Use the commandsCycling through the panes Changing pane focus Fs regs Foc next Changing the register display Scrolling panes Changing the pane size Refreshing and updating the window XDB to WDB Transition Guide By-function lists of XDB commands and HP WDB equivalents Window mode commands Invocation commandsInvocation commands Window mode commands File viewing commands File viewing commands Data Viewing and modification commands Source directory mapping commands Ll string Lm string Data viewing and modification commands Stack viewing commands Stack viewing commands Job control commands Status-viewing commandStatus viewing commands Job control commands Auxiliary breakpoint commands Overall breakpoint commandsOverall breakpoint commands Auxillary breakpoint commands Breakpoint creation commands10 Breakpoint creation commands 11 Overall breakpoint commands Breakpoint status commands Global breakpoint commands All-procedures breakpoint commands12 Global breakpoint commands Bp bpt bpx dp Dpt Dpx Record and playback commands Assertion control commandsMacro facility commands Miscellaneous commands Signal control commands13 Macro facility commands 14 Signal control commands 16 Data format commands Format of the print command is different in XDB and GDBXDB data formats and HP WDB equivalents Decimal integer XDB location syntax and HP WDB equivalents 17 Macro facility commandsXDB special language operators and HP WDB equivalents 18 Special language operators XDB special variables and HP WDB equivalents19 Special variables XDB variable identifiers and HP WDB equivalents Alphabetical lists of XDB commands and HP WDB equivalents16.8.1 a 20 Variable Identifiers 22 B 16.8.2 B 23 C through D Through D 16.8.5 L Through K24 F through K 25 L 26 M through P Through P 16.8.8 T Through S27 Q through S 28 T 29 U through Z Through Z 30 Symbols Symbols Any string Control-C # text 280 Setting Command Editing Options in GDB Setting the GDB PromptSetting Command History Feature in GDB Controlling GDB To fname. This is the file where GDB reads an Control the settingsExits. You can access this list through history Expansion or through the history command Supported Number Formats Setting the GDB Screen Size Optional warnings and messages Set confirm on Optional messages about internal happeningsShow confirm Displays state of confirmation requests Object debugging info Show debug varobj User-defined commands Canned Sequences of Commands User-defined command hooks To add source directories or Command files Commands for controlled output Output formats Expressions 292 Using GDB under gnu Emacs Execute to next instruction, using the GDB nexti command Calls, like the GDB next command. Then update the displayUpdate display window accordingly GDB up command 295 296 GDB Annotations What is an annotation?Server prefix Values When printing a structure, GDB annotates it as follows Frames When printing an array, GDB annotates it as followsFrame annotation begins with Then comes Annotation for GDB input Displays Information on breakpoints Errors Running the program Invalidation notices Displaying source Target-invalid Annotations We Might Want in the Future 306 GDB/MI Interface 21.1 GDB/MI Command Syntax 21.1.2 GDB/MI Output syntax Done running connected error exitPragmatics Value Const tuple list String Tuple → 21.2 GDB/MI compatibility with CLI Here is what happens if you pass a bad commandSimple examples of GDB/MI interaction Here is an example to evaluate an expression 21.3 GDB/MI output records 21.4 GDB/MI command description format21.3.1 GDB/MI result records 21.3.2 GDB/MI stream records -break-after Command 21.5 GDB/MI breakpoint table commands Corresponding GDB command is condition -break-condition command -break-disable command -break-delete commandCorresponding GDB command is delete Corresponding GDB command is disable -break-info Command -break-enable command Result -break-insert command -break-list command Corresponding GDB commands are watch, awatch, and rwatch -break-watch commandSetting a watchpoint on a variable in the main function Exec-continue running gdb 21.6 GDB/MI Data manipulation -data-disassemble command Disassemble from the current value of $pc to $pc + There is no direct mapping from this command to the CLIDisassemble 3 instructions from the start of main -data-evaluate-expression command -data-list-register-names command -data-list-changed-registers CommandDisplay a list of the registers that have changed On a PPC MBX board -data-list-register-values command Space should be quoted using the C convention -data-read-memory commandTo be read. Complex expressions containing embedded white Word-format Word-sizenr-rowsnr-cols aschar -display-disable Command -display-delete command -display-insert Command -display-enable command-display-list command -environment-cd command -environment-path command -environment-directory command Corresponding GDB command is pwd -environment-pwd command21.7 GDB/MI program control Show the current working directory -exec-arguments command -exec-abort command-exec-continue command -exec-interrupt command -exec-finish commandCorresponding GDB command is finish Corresponding GDB command is interrupt -exec-next-instruction command -exec-nextcommand SynopsisCorresponding GDB command is next Corresponding GDB command is nexti -exec-runcommand Synopsis -exec-return commandCorresponding GDB command is return Corresponding GDB command is run Example -exec-stepCommand Synopsis -exec-show-arguments command -exec-until command -exec-step-instruction commandCorresponding GDB command is stepi Regular stepping -file-exec-file command -file-exec-and-symbols commandCorresponding GDB command is until Corresponding GDB command is file -file-list-exec-source-files command -file-list-exec-sections command-file-list-shared-libraries command -file-list-symbol-files command Miscellaneous GDB commands in GDB/MI-file-symbol-file command -gdb-exitcommand Synopsis -gdb-showcommand Synopsis -gdb-setcommand Synopsis-gdb-version command -stack-info-frame command 21.9 GDB/MI Stack Manipulation Commands-stack-info-depth command For a stack with frame levels 0 through -stack-list-arguments command Synopsis -stack-list-frames command Full stack backtrace Corresponding GDB commands are backtrace and whereShow frames between lowframe and highframe Show a single frame -stack-select-frame command -stack-list-locals commandInfo locals in GDB, gdbgetlocals in gdbtk -symbol-info-address command 21.10 GDB/MI Symbol query commands-symbol-info-file command -symbol-info-function command -symbol-info-symbol command -symbol-info-line command-symbol-list-functions command -symbol-list-types command -symbol-locate command -symbol-list-variables command-symbol-type command -target-attach command 21.11 GDB/MI Target Manipulation Commands-target-compare-sections command -target-detach command Corresponding GDB command is load -target-download commandName of the section At the end, a summary is printed -target-exec-status command -target-list-current-targets command -target-list-available-targets command-target-list-parameters command -target-select command 21.12 GDB/MI thread commands-thread-info command -thread-list-all-threads command -thread-select command -thread-list-ids command Tracepoint commands are not yet implemented 21.13 GDB/MI tracepoint commands21.14 GDB/MI variable objects GDB/MI Operations -var-create commandDescription and use of operations on variable objects -var-set-format command -var-delete command-var-show-format command -var-info-num-children command -var-info-type command -var-list-children command-var-info-expression command -var-show-attributes command -var-update command -var-assign command 360 Reporting Bugs in GDB How to report bugsHave you found a bug? Reporting Bugs in GDB How to report bugs 364 Installing GDB Gdb-gdb-199991101/mmalloc Compiling GDB in another directoryPackage Specifying names for hosts and targets Separate directories. configure writes configuration Configure optionsTo use the source in the directory dirname. configure Srcdir= dirname All available targets Target=target