optimization - How can I speed up Perl's processing of fixed-width data? -

-

We have a mature body of code that loads data from files into the database; there are many file formats; They are all fixed-width areas.

Part of the code uses Perl Unpack () function to read fields from the input data in the package variable. Business logic is able to refer to these areas in 'human-readable' manner.

File readings are generated from a format description before reading the file format.

In the sketch form, the generated code looks like this: 

  while ( & gt;) {# generates the generated code # Here we open 2 fields , The real code is around 200. ($ FIELDS :: transaction_date, $ FIELDS :: customer_id) = unpack q {A8 A20}; # A key place has been removed in some areas # Generated code has a line similar to an affected line. $ FIELDS :: customer_id = ~ s / ^ \ s + //; # End of Generated Code # If we apply business logic for data ... if ($ FIELDS :: transaction_date eq $ today) {push @ fields, q {some or other}; } Write on the standard format for bulk loads in the database. Join print $ FH ('|', @fields). Q {\ n} or die; }

The code outline shows that about 35% of the time is spent on unpack and leading position bar. The rest of the time is spent in data validation and converting and writing in the output file.

It seems that there is no part of business logic that takes more than 1-2% of run time.

The question is whether we can touch somehow in some way and move a little further than the place?

Edit:

If a difference makes

ex> $ perl -v it Perl for Perl, v5.8.0

Yes substrate < This is the fastest way to remove using / code>. That is: $ FIELDS :: transaction_date = substr $ _, 0, 8; $ FIELDS :: customer_id = substr $ _, 8, 20;

is likely to be faster now, if I was writing this code, then I would not leave unpack , but if you prepare the code If you are, you can give it shot and remedy too.

See

can also be the fastest way to snatch key locations, s / ^ \ s + // .

Update: It is difficult to say anything definite without being able to run the benchmark. However, about how: 

  my $ x = substr $ _, 0, 8; For those areas

no trimming is required and 

  my ($ y) = substr ($ _, 8, 20) = ~ / \ A (.? +) \ S + \ s + \ z /;

Is that necessary to fold?


Comments

Post a Comment

Popular posts from this blog

MySql variables and php -

-
I am getting an error with php in order to format mysql_query () in php to format this string What is the right way? SELECT SELECT SELECT (*) Agents @AgentCount; User_Agent_English, User_Angent_Oursal, US.___Gent_Aginal, COUNT (User_Agent_Percade) ACC, COUNT (*) / (AgentCount) Percentage by agents user_agent_preser order DEC limit limit 50; In PHP, how am i setting $ query $ query = "SELECT count (*) agents @ agentcount; SELECT user_agent_parsed, User_agent_original , COUNT (user_agent_parsed) ascount, COUNT (*) / (@AgentCount) as a percentage by user_agent_parced by URI date DESC limit 50 "; This exact query will work properly if I put it in MySQL directly through a command line session. Do I need to release two separate php calls from mysql_query () and store the results first? I get the following error: There is an error in your SQL syntax; Instead of using a sub-selection and instead of using the 'SELECT user_agent_parsed, user_agent_original, ne...
Read more

url rewriting - How to implement the returnurl like SO in PHP? -

-
This URL should work even after the rewrite. Is this possible? Otherwise, I can only hardcoded everything If you are trying to create a login system with redirection You need to use the HTTP_REFERER header to find out where the user came from so that you can send it back there. The best way to do this is to use something like this in your login form: // - Login php & Lt; Input type = "password" name = "password" /> & Lt; Input type = "hidden" name = "returnrelale" value = "& lt ;? php echo $ redirectURL ;? & gt;" / & Gt; & Lt; / Form & gt; Please note that some ISP, browser or proxy will delete the referrer header, so you can not rely on each user to work fully. If you use a statement, to check whether the header exists or not, you can send those users back to the homepage or whatever. Edit If you are looking to use $ _SERVER ['REQUEST_URI'], if you are running Apache It sho...
Read more

Which Python client library should I use for CouchdB? -

-
I am starting to experiment with CouchDB because it looks like we have the right solution to certain problems That all the work will be on a new project, which does not have any legacy dependency, which the client library will suggest you use, and why? If we overlap any of the OS. Freeband is available only in the collection of its ports, but asks to use the library's project website. None of those people are Ubuntu, which is only with ships, since those two OSAs are not common in libraries, I am probably installing something from source (and hopefully if I have time, then Ubuntu and FreeBSD People pack the package). For those interests, I want to use CouchDB as a convenient intermediate storage space for data passed between different services - think of a message bus system, but less formalities with. For example, we have daemons that download and pars the web page, then send an interesting bit to other daemons for further processing. Many of them are ill-defined until the...
Read more