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nexedi
ZODB
Commits
130c9dbc
Commit
130c9dbc
authored
Sep 27, 2016
by
Frances Wong
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Fixed typos in the Transactions and Threading page.
parent
8a61d748
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doc/guide/transactions-and-threading.rst
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doc/guide/transactions-and-threading.rst
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130c9dbc
...
...
@@ -151,7 +151,7 @@ them with the ``with`` statement directly::
When
used
as
a
context
manager
,
a
transaction
manager
explicitly
begins
a
new
transaction
,
executes
the
code
block
and
commits
the
transaction
if
there
isn
't an error and aborts it
o
f there is an
transaction
if
there
isn
't an error and aborts it
i
f there is an
error.
We used ``as trans`` above to get the transaction.
...
...
@@ -242,7 +242,7 @@ connections will get a conflict error when it tries to commit::
...
ZODB
.
POSException
.
ConflictError
:
...
If
we
executed
this
code
,
we
'd get ``ConflictError`` exception on the
If
we
executed
this
code
,
we
'd get
a
``ConflictError`` exception on the
last line. After a conflict error is raised, we'
d
need
to
abort
the
transaction
,
or
begin
a
new
one
,
at
which
point
we
'd see the data as
written by the other connection:
...
...
@@ -267,7 +267,7 @@ Retrying transactions
~~~~~~~~~~~~~~~~~~~~~
The most common way to deal with conflict errors is to catch them and
retry transactions. To do this manually
,
involves code that looks
retry transactions. To do this manually involves code that looks
something like this::
max_attempts = 3
...
...
@@ -325,12 +325,12 @@ Commonly used objects that implement conflict resolution are
buckets and ``Length`` objects provided by the `BTree
<https://pythonhosted.org/BTrees/>`_ package.
The main data structures provided by BTrees
:
BTrees and TreeSets,
The main data structures provided by BTrees
,
BTrees and TreeSets,
spread their data over multiple objects. The leaf-level objects,
called *buckets*, allow distinct keys to be updated without causing
conflicts [#usually-avoids-conflicts]_.
``Length`` objects are conflict-free counters
,
that merge changes by
``Length`` objects are conflict-free counters that merge changes by
simply accumulating changes.
.. caution::
...
...
@@ -353,7 +353,7 @@ can be broken in non-obvious ways. For example a Web API that splits
logical operations over multiple web requests, as is often done in
`REST
<https://en.wikipedia.org/wiki/Representational_state_transfer>`_
APIs, violate this rule.
APIs, violate
s
this rule.
Partial transaction error recovery using savepoints
---------------------------------------------------
...
...
@@ -395,7 +395,7 @@ ZODB supports concurrency through transactions. Multiple programs
[#
wtf
-
program
]
_
can
operate
independently
in
separate
transactions
.
They
synchronize
at
transaction
boundaries
.
The
most
common
way
to
run
ZODB
is
with
each
program
running
in
it
'
s
The
most
common
way
to
run
ZODB
is
with
each
program
running
in
its
own
thread
.
Usually
the
thread
-
local
transaction
manager
is
used
.
You
can
use
multiple
threads
per
transaction
and
you
can
run
multiple
...
...
@@ -441,7 +441,7 @@ Some things to keep in mind when utilizing multiple processes:
split due to added objects causing them to exceed their maximum size.
.. [#undo] Transactions can'
t
be
rolled
back
,
but
they
may
be
undone
in some cases, especially
o
f subsequent transactions
in
some
cases
,
especially
i
f
subsequent
transactions
haven
't modified the same objects.
.. [#bad-idea-using-multiple-threads-per-transaction] While it'
s
...
...
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