JupyterHub

psana2 is also available in JupyterHub here in the kernel named "LCLS-II py3": https://pswww.slac.stanford.edu/jupyterhub/hub/home

Environment

To obtain the environment to run psana2, execute the following:

source /cds/sw/ds/ana/conda2/manage/bin/psconda.sh

Note that LCLS-II psana is not compatible with LCLS-I psana, so environments must activate one or the other, but not both.

Public Practice Data

Publicly accessible practice data is located in the directory /cds/data/psdm/prj/public01/xtc. Use of this data requires the additional "dir=" keyword to the DataSource object.

Experiment	Run	Comment
tmoc00118	222	Generic TMO dark data

Detector Names

Use this command to see non-epics detector names (see "Detector Interface" example below):

(ps-4.1.0) psanagpu101:lcls2$ detnames exp=tmoc00118,run=222,dir=/cds/data/psdm/prj/public01/xtc
---------------------
Name      | Data Type
---------------------
epicsinfo | epicsinfo
timing    | raw      
hsd       | raw      
gmdstr0   | raw    
etc.

Use the same command with the "-e" option to see epics detector names (see "Detector Interface" example below). These are slowly varying variables (like temperatures) that are not strongly time correlated with the regular per-shot detector data:

(ps-4.1.0) psanagpu101:lcls2$ detnames -e exp=tmoc00118,run=123
---------------------------
Name            | Data Type
---------------------------
StaleFlags      | raw      
Keithley_Sum    | raw      
IM2K4_XrayPower | raw      
IM3K4_XrayPower | raw 
etc.

Using the Detector Interface

Standard (per-shot) detectors and the slower epics variables can be accessed as shown here using the names discovered with the commands above. You can use tab-completion in ipython or the jupyter notebook to explore what you can do with the various detector objects:

from psana import DataSource
ds = DataSource(exp='tmoc00118', run=222, dir='/cds/data/psdm/prj/public01/xtc', max_events=10)
myrun = next(ds.runs())
opal = myrun.Detector('tmoopal')
epics_det = myrun.Detector('IM2K4_XrayPower')
for evt in myrun.events():
    img = opal.raw.image(evt)
    epics_val = epics_det(evt)
	# check for missing data
    if img is None or epics_val is None:
        print('none')
        continue
    print(img.shape,epics_val)

Example Script Producing Small HDF5 File

You can run this script with MPI: mpirun -n 6 python example.py

It also works on one core with: python example.py (useful for debugging). See MPI rank/task diagram here to understand what different mpi ranks are doing.

This mechanism by defaults produces "aligned" datasets where missing values are padded (with NaN's for floats, and -99999 for integers). To create an unaligned dataset (without padding) prefix the name of the variable with "unaligned_".

NOTE: in addition to the hdf5 you specify as your output file ("my.h5" below) you will see other h5 files like "my_part0.h5", one for each of the cores specified in PS_SRV_NODES. The reason for this is that each of those cores writes its own my_partN.h5 file: for LCLS2 it will be important for performance to write many files. The "my.h5" file is actually quite small, and uses a new HDF5 feature called a "Virtual DataSet" (VDS) to join together the various my_partN.h5 files. Also note that events in my.h5 will not be in time order. If you copy the .h5 somewhere else, you need to copy all of them.

NOTE: In python, if you want to exit early you often use a "break" statement. When running psana-python with mpi parallelization, however, not all cores will see this statement, and the result will be that your job will hang at the end. To avoid this use the "max_events" keyword argument to DataSource (see example below).

from psana import DataSource
import numpy as np
import os

# OPTIONAL callback with "gathered" small data from all cores.
# usually used for creating realtime plots when analyzing from
# DAQ shared memory. Called back on each SRV node.
def my_smalldata(data_dict):
    print(data_dict)

# sets the number of h5 files to write. 1 is sufficient for 120Hz operation
# optional: only needed if you are saving h5.
os.environ['PS_SRV_NODES']='1'

ds = DataSource(exp='tmoc00118', run=222, dir='/cds/data/psdm/prj/public01/xtc', max_events=10)
# batch_size is optional. specifies how often the dictionary of small
# user data is gathered
smd = ds.smalldata(filename='mysmallh5.h5', batch_size=5, callbacks=[my_smalldata])

for run in ds.runs():
    opal = run.Detector('tmo_opal1')
    ebeam = run.Detector('ebeam')
 
    runsum  = 0
    for evt in run.events():
        img = opal.raw.image(evt)
        photonEnergy = ebeam.raw.ebeamPhotonEnergy(evt)
        if img is None or photonEnergy is None: continue
        evtsum = np.sum(img)
        # pass either dictionary or kwargs
        smd.event(evt, evtsum=evtsum, photonEnergy=photonEnergy)
        runsum += evtsum # beware of datatypes when summing: can overflow
 
    # optional summary data for whole run
    if smd.summary:
        smd.sum(runsum) # sum across all mpi cores
        # pass either dictionary or kwargs
        smd.save_summary({'sum_over_run' : runsum}, summary_int=1)
    smd.done()

Full Featured Example with Callbacks and Detector Selection

You can run this script with MPI the same way as previous example: mpirun -n 6 python example.py

Three more arguments for DataSource were added to this example

detectors=['detname1', 'detname2',]

List of detectors to be read from the disk. If you only need a few detectors, list their name here. The reading process will be faster since we don't need to read other detectors.

filter= filter_fn

You can write a filter_fn(evt) callback which returns True or False to include or exclude the event from getting read from the disk.

small_xtc=['detname1', 'detname2']

List of detectors to be used in filter_fn()

destination=destination

You can write a destination(evt) callback with returns rank id that you want to send this event to.

from psana import DataSource
import numpy as np
import os

# OPTIONAL callback with "gathered" small data from all cores.
# usually used for creating realtime plots when analyzing from
# DAQ shared memory. Called back on each SRV node.
def my_smalldata(data_dict):
    print(data_dict)

# Use this function to decide to keep/discard this event
# If this detector is needed, make sure to define this
# detector in as_smds argument for DataSource (see below)
def filter_fn(evt):
    run = evt.run()
    step = run.step(evt)
    opal = run.Detector('tmo_opal1')
    img = opal.raw.image(evt)
    return True

# Use this function to direct an event to process on a
# particular 'rank'. This function should returns a rank
# number between 2 to no. of total ranks - 1.
def destination(evt):
    # Note that run, step, and det can be accessed
    # the same way as shown in filter_fn
    n_bd_nodes = 3 # for mpirun -n 6, 3 ranks are reserved so there are 3 bd ranks left
    dest = (evt.timestamp % n_bd_nodes) + 1
    return dest

# sets the number of h5 files to write. 1 is sufficient for 120Hz operation
# optional: only needed if you are saving h5.
os.environ['PS_SRV_NODES']='1'

ds = DataSource(exp='tmoc00118', run=222, dir='/cds/data/psdm/prj/public01/xtc', 
        max_events  = 10,   
        detectors   = ['tmo_opal1', 'ebeam'],   # only reads these detectors (faster)
        filter      = filter_fn,                # filter_fn returns True/False
        small_xtc   = ['tmo_opal1'],            # detectors to be used in filter callback
        destination = destination)              # returns rank no. (send this evt to this rank)

# batch_size is optional. specifies how often the dictionary of small
# user data is gathered
smd = ds.smalldata(filename='mysmallh5.h5', batch_size=5, callbacks=[my_smalldata])

for run in ds.runs():
    opal = run.Detector('tmo_opal1')
    ebeam = run.Detector('ebeam')
 
    runsum  = 0
    for evt in run.events():
        img = opal.raw.image(evt)
        photonEnergy = ebeam.raw.ebeamPhotonEnergy(evt)
        if img is None or photonEnergy is None: continue
        evtsum = np.sum(img)
        # pass either dictionary or kwargs
        smd.event(evt, evtsum=evtsum, photonEnergy=photonEnergy)
        runsum += evtsum # beware of datatypes when summing: can overflow
 
    # optional summary data for whole run
    if smd.summary:
        smd.sum(runsum) # sum across all mpi cores
        # pass either dictionary or kwargs
        smd.save_summary({'sum_over_run' : runsum}, summary_int=1)
    smd.done()

Running in Parallel

Instructions for submitting batch jobs to run in parallel are here: Batch System Analysis Jobs

MPI Task Structure

To allow for scaling, many hdf5 files are written, one per "SRV" node. The total number of SRV nodes is defined by the environment variable PS_SRV_NODES (defaults to 0). These many hdf5 files are joined by psana into what appears to be one file using the hdf5 "virtual dataset" feature.

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