Dear all,
unto now I had been thinking this is a wise idiom (in code
that needs not care whether it fails to do what it tries to
do^1):
conn = psycopg2.connection(...)
curs = conn.cursor()
try:
curs.execute(SOME_SQL)
except PSYCOPG2-Exception:
some logging being done, and, yes, I
can safely inhibit propagation^1
finally:
conn.commit() # will rollback, if SOME_SQL failed
conn.close()
So today I head to learn that conn.commit() may very well
raise a DB related exception, too:
psycopg2.errors.SerializationFailure: could not serialize access due to
read/write dependencies among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during
commit attempt.
TIP: The transaction might succeed if retried.
Now, what is the proper placement of the .commit() ?
(doing "with ... as conn:" does not free me of committing appropriately)
Should I
try:
curs.execute(SOME_SQL)
conn.commit()
except PSYCOPG2-Exception:
some logging being done, and, yes, I
can safely inhibit propagation^1
finally:
conn.close() # which should .rollback()
automagically in case we had not reached to .commit()
?
Thanks for insights,
Karsten
#-------------------------------
^1:
This particular code is writing configuration defaults
supplied in-code when no value is yet to be found in the
database. If it fails, no worries, the supplied default
is used by follow-on code and storing it is re-tried next
time around.
#-------------------------------
Exception details:
Traceback (most recent call last):
File "/usr/share/gnumed/Gnumed/wxpython/gmGuiMain.py", line 3472, in
OnInit
frame = gmTopLevelFrame(None, id = -1, title = _('GNUmed client'),
size = (640, 440))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/gnumed/Gnumed/wxpython/gmGuiMain.py", line 191, in
__init__
self.LayoutMgr = gmHorstSpace.cHorstSpaceLayoutMgr(self, -1)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/gnumed/Gnumed/wxpython/gmHorstSpace.py", line 215,
in __init__
self.top_panel = gmTopPanel.cTopPnl(self, -1)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/gnumed/Gnumed/wxpython/gmTopPanel.py", line 52, in
__init__
wxgTopPnl.wxgTopPnl.__init__(self, *args, **kwargs)
File "/usr/share/gnumed/Gnumed/wxGladeWidgets/wxgTopPnl.py", line 33,
in __init__
self._TCTRL_patient_selector = cActivePatientSelector(self,
wx.ID_ANY, "")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/gnumed/Gnumed/wxpython/gmPatSearchWidgets.py", line
1295, in __init__
cfg.get2 (
File "/usr/share/gnumed/Gnumed/pycommon/gmCfg.py", line 248, in get2
self.set (
File "/usr/share/gnumed/Gnumed/pycommon/gmCfg.py", line 367, in set
rw_conn.commit() # will rollback if transaction failed
^^^^^^^^^^^^^^^^
psycopg2.errors.SerializationFailure: could not serialize access due to
read/write dependencies among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during
commit attempt.
TIP: The transaction might succeed if retried.
2024-08-20 22:17:04 INFO gm.cfg [140274204403392
UpdChkThread-148728] (/usr/share/gnumed/Gnumed/pycommon/gmCfg.py::get2()
#148): creating option [horstspace.update.consider_latest_branch] with default
[True]
2024-08-20 22:17:04 DEBUG gm.db_pool [140274459512896
MainThread]
(/usr/share/gnumed/Gnumed/pycommon/gmConnectionPool.py::exception_is_connection_loss()
#667): interpreting: could not serialize access due to read/write dependencies
among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during
commit attempt.
TIP: The transaction might succeed if retried.
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#170): exception: could not serialize access due to read/write dependencies
among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during
commit attempt.
TIP: The transaction might succeed if retried.
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#171): type: <class 'psycopg2.errors.SerializationFailure'>
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#172): list of attributes:
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): add_note: <built-in method add_note of SerializationFailure object at
0x7f942a3c9cf0>
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): args: ('could not serialize access due to read/write dependencies
among transactions\nDETAIL: Reason code: Canceled on identification as a
pivot, during commit attempt.\nTIP: The transaction might succeed if
retried.\n',)
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): cursor: None
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): diag: <psycopg2.extensions.Diagnostics object at 0x7f942a2b9e10>
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): pgcode: 40001
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): pgerror: ERROR: could not serialize access due to read/write
dependencies among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during
commit attempt.
TIP: The transaction might succeed if retried.
2024-08-20 22:17:04 DEBUG gm.logging [140274459512896
MainThread] (/usr/share/gnumed/Gnumed/pycommon/gmLog2.py::log_stack_trace()
#178): with_traceback: <built-in method with_traceback of
SerializationFailure object at 0x7f942a3c9cf0>
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