Getting Started

kdb+ is very customisable. Customisations are contained in q scripts (.q files), which define functions and variables which modify the behaviour of a process. Every q process can load a single q script, or a directory containing q scripts and/or q data files. Hooks are provided to enable the programmer to apply a custom function to each entry point of the process (.z.p*), to be invoked on the timer (.z.ts) or when a variable in the top level namespace is amended (.z.vs). By default none of these hooks are implemented.

We provide a codebase and a single main script, torq.q. torq.q is essentially a wrapper for bespoke functionality which can load other scripts/directories, or can be sourced from other scripts. Whenever possible, torq.q should be invoked directly and used to load other scripts as required. torq.q will:

  • ensure the environment is set up correctly;

  • define some common utility functions (such as logging);

  • execute process management tasks, such as discovering the name and type of the process, and re-directing output to log files;

  • load configuration;

  • load the shared code based;

  • set up the message handlers;

  • load any required bespoke scripts.

The behavior of torq.q is modified by both command line parameters and configuration. We have tried to keep as much as possible in configuration files, but if the parameter either has a global effect on the process or if it is required to be known before the configuration is read, then it is a command line parameter.

Using torq.q

torq.q can be invoked directly from the command line and be set to source a specified file or directory. torq.q requires the 5 environment variables to be set (see section envvar). If using a unix environment, this can be done with the setenv.sh script. To start a process in the foreground without having to modify any other files (e.g. process.csv) you need to specify the type and name of the process as parameters. An example is below.

$ . setenv.sh
$ q torq.q -debug -proctype testproc -procname test1

To specify the parent process type, do:

$ q torq.q -debug -parentproctype testparentproc -proctype testproc -procname test1

To load a file, do:

$ q torq.q -load myfile.q -debug -proctype testproc -procname test1

It can also be sourced from another script. If this is the case, some of the variables can be overridden, and the usage information can be modified or extended. Any variable that has a definition like below can be overridden from the loading script.

myvar:@[value;`myvar;1 2 3]

The available command line parameters are:

Cmd Line Param Description
-procname x -proctype y The process name and process type
-parentproctype x The parent process type
-procfile x The name of the file to get the process information from
-load x [y..z] The files or database directory to load
-loaddir x [y..z] Load all .q, .k files in specified directories
-localtime Sets processes running in local time rather than GMT for log messages, timer calls etc. The change is backwards compatible; without -localtime flag the process will print logs etc. in GMT but can also have a different .z.P
-trap Any errors encountered during initialization when loading external files will be caught and logged, processing will continue
-stop Stop loading the file if an error is encountered but do not exit
-noredirect Do not redirect std out/std err to a file (useful for debugging)
-noredirectalias Do not create an alias for the log files (aliases drop any suffix e.g. timestamp suffix)
-noconfig Do not load configuration
-nopi Reset the definition of .z.pi to the initial value (useful for debugging)
-debug Equivalent to [-nopi -noredirect]
-usage Print usage info and exit
-onelog Writes all messages to stdout log file, note non-trapped errors will still be written to stderr log file

In addition any process variable in a namespace (.*.*) can be overridden from the command line. Any value supplied on the command line will take priority over any other predefined value (.e.g. in a configuration or wrapper). Variable names should be supplied with full qualification e.g. -.servers.HOPENTIMEOUT 5000.

Using torq.sh

torq.sh is a script that runs processes in torq with added functionality, one key enhancement is all the process configuration is now in one place. The default process file is located in $KDBCONFIG/process.csv. This script is only available on Linux. It requires environment variables to be set, similar to torq.q. A usage statement for the script can be seen by running the following in a unix environment: ./torq.sh.

Environment Variables

Five environment variables are required:

Environment Variable Description
KDBCONFIG The base configuration directory
KDBCODE The base code directory
KDBLOGS Where standard out/error and usage logs are written
KDBHTML Contains HTML files
KDBLIB Contains supporting library files

torq.q will check for these and exit if they are not set. If torq.q is being sourced from another script, the required environment variables can be extended by setting .proc.envvars before loading torq.q.

Process Identification

At the crux of AquaQ TorQ is how processes identify themselves. This is defined by two required variables - .proc.proctype and .proc.procname which are the type and name of the process respectively. An optional variable parentproctype allows an inital codebase and configuration to be loaded. The two required values determine the code base and configuration loaded, and how they are connected to by other processes. If both of the required variables are not defined, TorQ will attempt to use the port number a process was started on to determine the code base and configuration loaded.

The most important of these is the proctype. It is up to the user to define at what level to specify a process type. For example, in a production environment it would be valid to specify processes of type “hdb” (historic database) and “rdb” (real time database). It would also be valid to segregate a little more granularly based on approximate functionality, for example “hdbEMEA” and “hdbAmericas”. In this example it may be sensible to set the parentproctype as "hdb" and putting all shared code in the "hdb" configuration to be loaded first with the region-specific configuration being loaded after. The actual functionality of a process can be defined more specifically, but this will be discussed later. The procname value is used solely for identification purposes. A process can determine its type and name in a number of ways:

  1. From the process file in the default location of $KDBCONFIG/process.csv;

  2. From the process file defined using the command line parameter -procfile;

  3. From the port number it is started on, by referring to the process file for further process details;

  4. Using the command line parameters -proctype and -procname;

  5. By defining .proc.proctype and .proc.procname in a script which loads torq.q.

For options 4 and 5, both parameters must be defined using that method or neither will be used (the values will be read from the process file).

For option 3, TorQ will check the process file for any entries where the port matches the port number it has been started on, and deduce it’s proctype and procname based on this port number and the corresponding hostname entry.

The process file has format as below.

aquaq$ cat config/process.csv 

The process will read the file and try to identify itself based on the host and port it is started on. The host can either be the value returned by .z.h, or the ip address of the server. If the process can not automatically identify itself it will exit, unless proctype and procname were both passed in as command line parameters. If both of these parameters are passed in then default configuration settings will be used.

The parameters following procname set the following:

Parameter Description
U Authentication requiring a usr:pwd file
localtime Sets process running in local time rather than GMT
g Garbage collection immediate (1) or deferred (0)
T Timeout in seconds for client queries, 0 for no timeout
w Workspace MB limit
load Files or database directory to load
startwithall Determine if process is started when all is specified
extras Specify any additional parameters
qcmd Allows different versions of q to be used or different command line options - rlwap, numactl

Where U/g/T/w are standard q command line arguments and localtime and load are TorQ command line parameters.

Running processes using torq.sh

torq.sh is able to start or stop processes seperately, in a batch or all at once. Before a process is started/stopped the script will check that the process is not already running before attempting to start/stop a process, a time of when this is executed is printed to screen.

$ ./torq.sh start rdb1 hdb1 tickerplant1
    15:42:00 | Starting rdb1...
    15:42:00 | hdb1 already running
    15:42:00 | Starting tickerplant1...

$ ./torq.sh stop all
    15:46:19 | Shutting down hdb1...
    15:46:19 | Shutting down hdb2...

A status summary table of all the processes can be printed to screen, the summary provides information on the time the process was checked, process name, status and the port number and PID of that process.

$ ./torq.sh summary
    TIME     | PROCESS        | STATUS | PORT   | PID
    11:33:59 | discovery1     | up     | 41001  | 14426
    11:33:59 | tickerplant1   | down   |

It is possible to view the underlying start code for all processes. This is useful if another available command line parameter was required for start up.

$ ./torq.sh print discovery1 
    Start line for discovery1:
    nohup q deploy/torq.q -procname discovery1 -stackid 41000 -proctype discovery -U appconfig/passwords/accesslist.txt -localtime 1 -g 0 -load deploy/code/processes/discovery.q -procfile deploy/appconfig/process.csv </dev/null > deploy/logs/torqdiscovery1.txt 2>&1 &

The debug command line parameter can be appended to the start line straight from torq.sh to start a process in debug mode. Note it is only possible to start one process at a time in debug mode.

$ ./torq.sh debug tickerplant1 

If a process name not present in the process.csv is used, the input process name will return as an invalid input. To see a list of all the processes in the process.csv see below.

$ ./torq.sh procs

A different process file can be used with this script from the command line. The argument following the csv flag needs to be a full path to the process.csv.

$ ./torq.sh start all -csv ${KDBAPPCONFIG}/process.csv

To add/override the default values in the g, T, w, or extras column the extras flag can be used in this script.

$ ./torq.sh start rdb1 -extras -T 60 -w 4000
$ ./torq.sh start sort1 -extras -s -3


By default, each process will redirect output to a standard out log and a standard error log, and create aliases for them. These will be rolled at midnight on a daily basis. They are all written to the $KDBLOGS directory. The log files created are:

Log File Description
out_[procname]_[date].log Timestamped out log
err_[procname]_[date].log Timestamped error log
out_[procname].log Alias to current log log
err_[procname].log Alias to current error log

The date suffix can be overridden by modifying the .proc.logtimestamp function and sourcing torq.q from another script. This could, for example, change the suffixing to a full timestamp.

In the case where -onelog is flagged TorQ will attempt to redirect all output to the out log file, unfortunately this is not perfect.

TorQ uses \1 and \2 to redirect stderr and stdout, onelog only overrides handled errors to the \1 redirect. This is because there are issuses with redirecting both to the same file, (the ordering of messages will be incorrect) the issue is with KDB+ rather than with TorQ.

Because of this errors that are raised by KDB+ and unhandled are still directed to the err log file because \1 and \2 cannot be redirected to the same file.

Configuration Loading

Default Configuration Loading

Default process configuration is contained in q scripts, and stored in the $KDBCONFIG /settings directory. Each process tries to load all the configuration it can find and will attempt to load three configuration files in the below order:-

  • default.q: default configuration loaded by all processes. In a standard installation this should contain the superset of customisable configuration, including comments.

  • [parentproctype].q: configuration for a specific parent process type (only if parentproctype specified).

  • [proctype].q: configuration for a specific process type.

  • [procname].q: configuration for a specific named process.

The only one which should always be present is default.q. Each of the other scripts can contain a subset of the configuration variables, which will override anything loaded previously.

Application Configuration Loading

Application specific configuration can be stored in a user defined directory and made visible to TorQ by setting the $KDBAPPCONFIG environment variable. If $KDBAPPCONFIG is set, then TorQ will search the $KDBAPPCONFIG/settings directory and load all configuration it can find. Application configuration will be loaded after all default configuration in the following order:-

  • default.q: Application default configuration loaded by all processes.

  • [[parentproctype]]{}.q : Application specific configuration for a specific parent process type (only if parentproctype specified).

  • [[proctype]]{}.q: Application specific configuration for a specific process type.

  • [[procname]]{}.q: Appliction specific configuration for a specific named process.

All loaded configuration will override anything loaded previously. None of the above scripts are required to be present and can contain a subset of the default configuration variables from the default configuration directory.

All configuration is loaded before code.

Application Dependency

TorQ will automatically check application version and dependency information. TorQ will check the $KDBAPPCONFIG directory for a dependency.csv file. This file should contain information in the format:

app version dependency
app0 1.0.0 app1 1.1.1;app2 2.1.0

TorQ will also search the $KDBCONFIG directory for the TorQ dependency.csv file. If any of the dependency versions exceed application versions, TorQ will exit and log the error.

If no dependency files are supplied, TorQ will run as normal. However, if only an application dependency file is supplied, TorQ will exit and log the error.

Each version number can be up to 5 digits in length, separated by '.' and the current kdb+ version will be automatically added with the format major.minor.yyyy.mm.dd

Code Loading

Code is loaded from the $KDBCODE directory. There is also a common codebase, a codebase for each process type, and a code base for each process name, contained in the following directories and loaded in this order:

  • $KDBCODE/common: shared codebase loaded by all processes;

  • $KDBCODE/[parentproctype]: code for a specific parent process type (only if parentproctype specified);

  • $KDBCODE/[proctype]: code for a specific process type;

  • $KDBCODE/[procname]: code for a specific process name;

For any directory loaded, the load order can be specified by adding order.txt to the directory. order.txt dictates the order that files in the directory are loaded. If a file is not in order.txt, it will still be loaded but after all the files listed in order.txt have been loaded.

In addition to loading code form $KDBCODE, application specific code can be saved in a user defined directory with the same structure as above, and made visible to TorQ by setting the $KDBAPPCODE environment variable.

If this environment variable is set, TorQ will load codebase in the following order.

  • $KDBCODE/common: shared codebase loaded by all processes;

  • $KDBAPPCODE/common: application specific code shared by all processes;

  • $KDBCODE/[parentproctype]: code for a specific parent process type (only if parentproctype specified);

  • $KDBAPPCODE/[parentproctype]: application specific code for a specific parent process type (only if parentproctype specified);

  • $KDBCODE/[proctype]: code for a specific process type;

  • $KDBAPPCODE/[proctype]: application specific code for a specific process type;

  • $KDBCODE/[procname]: code for a specific process name;

  • $KDBAPPCODE/[procname]: application specific code for a specific process name;

Additional directories can be loaded using the -loaddir command line parameter.

Initialization Errors

Initialization errors can be handled in different ways. The default action is any initialization error causes the process to exit. This is to enable fail-fast type conditions, where it is better for a process to fail entirely and immediately than to start up in an indeterminate state. This can be overridden with the -trap or -stop command line parameters. With -trap, the process will catch the error, log it, and continue. This is useful if, for example, the error is encountered loading a file of stored procedures which may not be invoked and can be reloaded later. With -stop the process will halt at the point of the error but will not exit. Both -stop and -trap are useful for debugging.