Dennis, 1. Yes, .readlines() work where .read() fails. Thanks for the suggestion - this has really given a big boost to the size of the data I can read. 2. Yes, I am running the python interpretation within the IDE (Spyder).
Thanks -----Original Message----- From: Python-list [mailto:python-list-bounces+pradipto.banerjee=adainvestments....@python.org] On Behalf Of Dennis Lee Bieber Sent: Friday, October 19, 2012 6:01 PM To: python-list@python.org Subject: Re: Python does not take up available physical memory On Fri, 19 Oct 2012 12:08:53 -0500, Pradipto Banerjee <pradipto.baner...@adainvestments.com> declaimed the following in gmane.comp.python.general: > Hi, > > I am trying to read a file into memory. The size of the file is around 1 GB. > I have a 3GB memory PC and the Windows Task Manager shows 2.3 GB available > physical memory when I was trying to read the file. I tried to read the file > as follows: 1) 32-bit Windows OS can only physically address 4GB BUT 2) Unless you have a SERVER version of windows, the most allocated to a user process is 2GB (there is a boot-time parameter which can configure WinXP [for example] to allow 3GB to user processes -- the last GB is always reserved for the OS) > Is there any reason why python can't read a 1GB file in memory even when a > 2.3 GB physical memory is available? Do I need to make a change in some > setting or preferences? > > I am using python(x,y) distribution (python 2.7) and use Spyder as the IDE. > Are you /running/ from within the IDE -- such that the Python interpreter is considered part of the IDE address space? <snipped> My first thought would be that you should NOT be loading an entire GB file as one chunk (for all I know, Windows low-level I/O read the file into a OS buffer [1GB] and then tries to pass it on to the Python memory buffer [another 1GB]... Or Python is reading in chunks -- say 1MB at a time, and appending chunks... That means it goes "whoops, I've got a 512MB data buffer and just read another 1MB -- better allocate a 768MB buffer [total now is 512 + 768 + 1 => 1281MB], copy the 512MB into the new buffer, append the 1MB, NOW free the older 512MB... You might have the raw memory, but it may be fragmented such that the system can not allocate a contiguous 1MB chunk). If .readlines() works when .read() fails, it is memory fragmentation (each parsed line is an individual chunk of memory since the list of lines is just a list of addresses to the lines) -- Wulfraed Dennis Lee Bieber AF6VN wlfr...@ix.netcom.com HTTP://wlfraed.home.netcom.com/ -- http://mail.python.org/mailman/listinfo/python-list This communication is for informational purposes only. It is not intended to be, nor should it be construed or used as, financial, legal, tax or investment advice or an offer to sell, or a solicitation of any offer to buy, an interest in any fund advised by Ada Investment Management LP, the Investment advisor. Any offer or solicitation of an investment in any of the Funds may be made only by delivery of such Funds confidential offering materials to authorized prospective investors. An investment in any of the Funds is not suitable for all investors. No representation is made that the Funds will or are likely to achieve their objectives, or that any investor will or is likely to achieve results comparable to those shown, or will make any profit at all or will be able to avoid incurring substantial losses. Performance results are net of applicable fees, are unaudited and reflect reinvestment of income and profits. Past performance is no guarantee of future results. All financial data and other information are not warranted as to completeness or accuracy and are subject to change without notice. Any comments or statements made herein do not necessarily reflect those of Ada Investment Management LP and its affiliates. This transmission may contain information that is confidential, legally privileged, and/or exempt from disclosure under applicable law. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or use of the information contained herein (including any reliance thereon) is strictly prohibited. If you received this transmission in error, please immediately contact the sender and destroy the material in its entirety, whether in electronic or hard copy format. -- http://mail.python.org/mailman/listinfo/python-list
