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• Django Deploy trouble

  - by i-Malignus

  Well, i've walking around this for a couples of days now... I think is time to ask for some help, i think my installation is ok... Server OS: Centos 5 Python -v 2.6.5 Django -v (1, 1, 1, 'final', 0) my apache conf: <VirtualHost *:80> DocumentRoot /opt/workshop ServerName taller.antell.com.py WSGIScriptAlias / /opt/workshop/workshop.wsgi WSGIDaemonProcess taller.antell.com.py user=ignacio group=ignacio processes=2 threads=25 ErrorLog /opt/workshop/apache.error.log CustomLog /opt/workshop/apache.custom.log combined <Directory "/opt/workshop"> Options +ExecCGI +FollowSymLinks -Indexes -MultiViews AllowOverride All Order allow,deny Allow from all </Directory> </VirtualHost> my mod_wsgi conf: import os import sys sys.path.append('/opt/workshop') os.environ['DJANGO_SETTINGS_MODULE'] = 'workshop.settings' os.environ['PYTHON_EGG_CACHE'] = '/tmp/.python-eggs' import django.core.handlers.wsgi application = django.core.handlers.wsgi.WSGIHandler( ) the error that i'm getting on my apache error log is: [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] mod_wsgi (pid=11459): Exception occurred processing WSGI script '/opt/workshop/workshop.wsgi'. [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] Traceback (most recent call last): [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/handlers/wsgi.py", line 241, in __call__ [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] response = self.get_response(request) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/handlers/base.py", line 134, in get_response [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return self.handle_uncaught_exception(request, resolver, exc_info) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/handlers/base.py", line 154, in handle_uncaught_exception [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return debug.technical_500_response(request, *exc_info) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/views/debug.py", line 40, in technical_500_response [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] html = reporter.get_traceback_html() [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/views/debug.py", line 114, in get_traceback_html [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return t.render(c) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/__init__.py", line 178, in render [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return self.nodelist.render(context) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/__init__.py", line 779, in render [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] bits.append(self.render_node(node, context)) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/debug.py", line 81, in render_node [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] raise wrapped [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] TemplateSyntaxError: Caught an exception while rendering: No module named vehicles [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] Original Traceback (most recent call last): [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/debug.py", line 71, in render_node [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] result = node.render(context) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/debug.py", line 87, in render [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] output = force_unicode(self.filter_expression.resolve(context)) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/__init__.py", line 572, in resolve [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] new_obj = func(obj, *arg_vals) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/template/defaultfilters.py", line 687, in date [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return format(value, arg) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/dateformat.py", line 269, in format [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return df.format(format_string) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/dateformat.py", line 30, in format [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] pieces.append(force_unicode(getattr(self, piece)())) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/dateformat.py", line 175, in r [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return self.format('D, j M Y H:i:s O') [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/dateformat.py", line 30, in format [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] pieces.append(force_unicode(getattr(self, piece)())) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/encoding.py", line 71, in force_unicode [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] s = unicode(s) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/functional.py", line 201, in __unicode_cast [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return self.__func(*self.__args, **self.__kw) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/translation/__init__.py", line 62, in ugettext [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return real_ugettext(message) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/translation/trans_real.py", line 286, in ugettext [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return do_translate(message, 'ugettext') [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/translation/trans_real.py", line 276, in do_translate [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] _default = translation(settings.LANGUAGE_CODE) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/translation/trans_real.py", line 194, in translation [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] default_translation = _fetch(settings.LANGUAGE_CODE) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/translation/trans_real.py", line 180, in _fetch [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] app = import_module(appname) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/importlib.py", line 35, in import_module [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] __import__(name) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] ImportError: No module named vehicles [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] mod_wsgi (pid=11463): Exception occurred processing WSGI script '/opt/workshop/workshop.wsgi'. [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] Traceback (most recent call last): [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/handlers/wsgi.py", line 241, in __call__ [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] response = self.get_response(request) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/handlers/base.py", line 73, in get_response [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] response = middleware_method(request) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/middleware/common.py", line 56, in process_request [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] if (not _is_valid_path(request.path_info) and [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/middleware/common.py", line 142, in _is_valid_path [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] urlresolvers.resolve(path) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/urlresolvers.py", line 303, in resolve [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] return get_resolver(urlconf).resolve(path) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/urlresolvers.py", line 218, in resolve [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] sub_match = pattern.resolve(new_path) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/urlresolvers.py", line 216, in resolve [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] for pattern in self.url_patterns: [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/urlresolvers.py", line 245, in _get_url_patterns [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/core/urlresolvers.py", line 240, in _get_urlconf_module [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] self._urlconf_module = import_module(self.urlconf_name) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] File "/opt/python2.6/lib/python2.6/site-packages/django/utils/importlib.py", line 35, in import_module [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] __import__(name) [Wed Apr 21 15:17:48 2010] [error] [client 190.128.226.122] ImportError: No module named vehicles.urls Please give my a hand, i stuck... Obviously is a problem with my vehicle module (the only one in the app), another thing is that when i try: [root@localhost workshop]# python manage.py runserver 0:8000 The app runs perfectly, i think that the problem is something near the wsgi conf, something is not clicking.... Tks... Update: workshop dir looks like... [root@localhost workshop]# ls -l total 504 -rw-r--r-- 1 root root 22706 Apr 21 15:17 apache.custom.log -rw-r--r-- 1 root root 408141 Apr 21 15:17 apache.error.log -rw-r--r-- 1 root root 0 Apr 17 10:56 __init__.py -rw-r--r-- 1 root root 124 Apr 21 11:09 __init__.pyc -rw-r--r-- 1 root root 542 Apr 17 10:56 manage.py -rw-r--r-- 1 root root 3326 Apr 17 10:56 settings.py -rw-r--r-- 1 root root 2522 Apr 21 11:09 settings.pyc drw-r--r-- 4 root root 4096 Apr 17 10:56 templates -rw-r--r-- 1 root root 381 Apr 21 13:42 urls.py -rw-r--r-- 1 root root 398 Apr 21 13:00 urls.pyc drw-r--r-- 2 root root 4096 Apr 21 13:44 vehicles -rw-r--r-- 1 root root 38912 Apr 17 10:56 workshop.db -rw-r--r-- 1 root root 263 Apr 21 15:30 workshop.wsgi vehicles dir [root@localhost vehicles]# ls -l total 52 -rw-r--r-- 1 root root 390 Apr 17 10:56 admin.py -rw-r--r-- 1 root root 967 Apr 21 13:00 admin.pyc -rw-r--r-- 1 root root 732 Apr 17 10:56 forms.py -rw-r--r-- 1 root root 2086 Apr 21 13:00 forms.pyc -rw-r--r-- 1 root root 0 Apr 17 10:56 __init__.py -rw-r--r-- 1 root root 133 Apr 21 11:36 __init__.pyc -rw-r--r-- 1 root root 936 Apr 17 10:56 models.py -rw-r--r-- 1 root root 1827 Apr 21 11:36 models.pyc -rw-r--r-- 1 root root 514 Apr 17 10:56 tests.py -rw-r--r-- 1 root root 989 Apr 21 13:44 tests.pyc -rw-r--r-- 1 root root 1035 Apr 17 10:56 urls.py -rw-r--r-- 1 root root 1935 Apr 21 13:00 urls.pyc -rw-r--r-- 1 root root 3164 Apr 17 10:56 views.py -rw-r--r-- 1 root root 4081 Apr 21 13:00 views.pyc Update 2: this is my settings.py # Django settings for workshop project. DEBUG = True TEMPLATE_DEBUG = DEBUG ADMINS = ( ('Ignacio Rojas', '[email protected]'), ('Fabian Biedermann', '[email protected]'), ) MANAGERS = ADMINS DATABASE_ENGINE = 'sqlite3' DATABASE_NAME = '/opt/workshop/workshop.db' DATABASE_USER = '' DATABASE_PASSWORD = '' DATABASE_HOST = '' DATABASE_PORT = '' # Local time zone for this installation. Choices can be found here: # http://en.wikipedia.org/wiki/List_of_tz_zones_by_name # although not all choices may be available on all operating systems. # If running in a Windows environment this must be set to the same as your # system time zone. TIME_ZONE = 'America/Asuncion' # Language code for this installation. All choices can be found here: # http://www.i18nguy.com/unicode/language-identifiers.html LANGUAGE_CODE = 'es-py' SITE_ID = 1 # If you set this to False, Django will make some optimizations so as not # to load the internationalization machinery. USE_I18N = True # Absolute path to the directory that holds media. # Example: "/home/media/media.lawrence.com/" MEDIA_ROOT = '' # URL that handles the media served from MEDIA_ROOT. Make sure to use a # trailing slash if there is a path component (optional in other cases). # Examples: "http://media.lawrence.com", "http://example.com/media/" MEDIA_URL = '' # URL prefix for admin media -- CSS, JavaScript and images. Make sure to use a # trailing slash. # Examples: "http://foo.com/media/", "/media/". ADMIN_MEDIA_PREFIX = '/media/' # Make this unique, and don't share it with anybody. SECRET_KEY = '11y0_jb=+b4^nq@2-fo#g$-ihk5*v&d5-8hg_y0i@*9$w8jalp' MIDDLEWARE_CLASSES = ( 'django.middleware.common.CommonMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', ) ROOT_URLCONF = 'workshop.urls' TEMPLATE_DIRS = ( # Put strings here, like "/home/html/django_templates" or "C:/www/django/templates". # Always use forward slashes, even on Windows. # Don't forget to use absolute paths, not relative paths. "/opt/workshop/templates" ) INSTALLED_APPS = ( 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'workshop.vehicles', ) TEMPLATE_CONTEXT_PROCESSORS = ( 'django.core.context_processors.auth', 'django.core.context_processors.debug', 'django.core.context_processors.i18n', 'django.core.context_processors.media', )

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• Authoritative sources about Database vs. Flatfile decision

  - by FastAl

  <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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• How do I prove I should put a table of values in source code instead of a database table?

  - by FastAl

  <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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• Null-free "maps": Is a callback solution slower than tryGet()?

  - by David Moles

  In comments to "How to implement List, Set, and Map in null free design?", Steven Sudit and I got into a discussion about using a callback, with handlers for "found" and "not found" situations, vs. a tryGet() method, taking an out parameter and returning a boolean indicating whether the out parameter had been populated. Steven maintained that the callback approach was more complex and almost certain to be slower; I maintained that the complexity was no greater and the performance at worst the same. But code speaks louder than words, so I thought I'd implement both and see what I got. The original question was fairly theoretical with regard to language ("And for argument sake, let's say this language don't even have null") -- I've used Java here because that's what I've got handy. Java doesn't have out parameters, but it doesn't have first-class functions either, so style-wise, it should suck equally for both approaches. (Digression: As far as complexity goes: I like the callback design because it inherently forces the user of the API to handle both cases, whereas the tryGet() design requires callers to perform their own boilerplate conditional check, which they could forget or get wrong. But having now implemented both, I can see why the tryGet() design looks simpler, at least in the short term.) First, the callback example: class CallbackMap<K, V> { private final Map<K, V> backingMap; public CallbackMap(Map<K, V> backingMap) { this.backingMap = backingMap; } void lookup(K key, Callback<K, V> handler) { V val = backingMap.get(key); if (val == null) { handler.handleMissing(key); } else { handler.handleFound(key, val); } } } interface Callback<K, V> { void handleFound(K key, V value); void handleMissing(K key); } class CallbackExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; private Callback<String, String> handler; public CallbackExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); handler = new Callback<String, String>() { public void handleFound(String key, String value) { found.add(key + ": " + value); } public void handleMissing(String key) { missing.add(key); } }; } void test() { CallbackMap<String, String> cbMap = new CallbackMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; cbMap.lookup(key, handler); } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } Now, the tryGet() example -- as best I understand the pattern (and I might well be wrong): class TryGetMap<K, V> { private final Map<K, V> backingMap; public TryGetMap(Map<K, V> backingMap) { this.backingMap = backingMap; } boolean tryGet(K key, OutParameter<V> valueParam) { V val = backingMap.get(key); if (val == null) { return false; } valueParam.value = val; return true; } } class OutParameter<V> { V value; } class TryGetExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; public TryGetExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); } void test() { TryGetMap<String, String> tgMap = new TryGetMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; OutParameter<String> out = new OutParameter<String>(); if (tgMap.tryGet(key, out)) { found.add(key + ": " + out.value); } else { missing.add(key); } } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } And finally, the performance test code: public static void main(String[] args) { int size = 200000; Map<String, String> map = new HashMap<String, String>(); for (int i = 0; i < size; i++) { String val = (i % 5 == 0) ? null : "value" + i; map.put("key" + i, val); } long totalCallback = 0; long totalTryGet = 0; int iterations = 20; for (int i = 0; i < iterations; i++) { { TryGetExample tryGet = new TryGetExample(map); long tryGetStart = System.currentTimeMillis(); tryGet.test(); totalTryGet += (System.currentTimeMillis() - tryGetStart); } System.gc(); { CallbackExample callback = new CallbackExample(map); long callbackStart = System.currentTimeMillis(); callback.test(); totalCallback += (System.currentTimeMillis() - callbackStart); } System.gc(); } System.out.println("Avg. callback: " + (totalCallback / iterations)); System.out.println("Avg. tryGet(): " + (totalTryGet / iterations)); } On my first attempt, I got 50% worse performance for callback than for tryGet(), which really surprised me. But, on a hunch, I added some garbage collection, and the performance penalty vanished. This fits with my instinct, which is that we're basically talking about taking the same number of method calls, conditional checks, etc. and rearranging them. But then, I wrote the code, so I might well have written a suboptimal or subconsicously penalized tryGet() implementation. Thoughts?

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• Red Gate Coder interviews: Alex Davies

  - by Michael Williamson

  Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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• VirtualBox - bridged adapter settings fail in Windows 7 host

  - by pcampbell

  Consider a Windows 7 host where the VirtualBox guest is configured to use Bridged Adapter. An exception is raised when starting this guest machine: Failed to open/create the internal network HostInterfaceNetworking (VERR_SUPDRV_COMPONENT_NOT_FOUND) Result Code: E_FAIL (0x80004005) What resolution is there to this problem for Bridged Adapters in VirtualBox? The solutions attempted: changed Adapter Type to all available choices. No changes. uninstall VirtualBox, reboot host, re-install VirtualBox. No change in behaviour. edited the machine's .xml file, wiping out all <Network> <Adapter> nodes. Had VirtualBox re-create those nodes. No change. Host Details Oracle VirtualBox 3.2.4 (release 62467) Windows 7 x86

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• Choice of operating systems for a Rackspace cloud installation

  - by riteshmnayak

  I am planning to use Rackspace cloud services to host a java web application and also run apace for wordpress and trac. What would be a stable operating system to host such an application. My requirements are that the core OS bundle should be minimalistic (so I can install only what I want), consume very little memory and be performant. I would also need it to contain softwares for the common lamp stack, J2EE stack etc. A supported package manager would be lovely. My choices are listed below. RHEL 5.3 or 5.4 Debian Lenny Ubuntu 8.04 onwards Centos 5.3 or 5.4 Arch 2009.02 Gentoo 2008.0 or 10.1 Fedora 11 or 12 PS: can somebody add the rackspace tag to this? Edit to remove this line as well. Thanks

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• how to fix "BusyBox v1.17.1 (Ubuntu 1:1.17.1-10ubuntu1) built-in shell (ash) Enter 'help' for a list of built-in commands?"

  - by Joseph

  So I was using Ubuntu when suddenly the whole thing froze up and I had to reboot. And from that moment on, the system when it is starting up, prompts this little selection menu: GNU GRUB version 1.99~rc1-13ubuntu3 Ubuntu, with Linux 2.6.38-10-generic ubuntu, with Linux 2.6.38-10-generic (recovery mode) Previous Linux versions Memory test (memtest86+) Memory test (memtest86+, serial console 115200) I have chosen all of the available choices but all I get is another command line system that reads: BusyBox v1.17.1 (Ubuntu 1:1.17.1-10ubuntu1) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs): And honestly I can't do anything with it. Does anyone have any idea of what is going on and how I can get Ubuntu to work again?

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• How to connect two monitors to a macbook pro?

  - by CIRK

  I have a 13" macbook pro, and I need much more space right now, so I decided to buy two smaller monitors. (these from LG). But I don't really know how will I connect them. I've seen some products like this Diamond BVU195, but it's not currently in stores in my country. I've found these Equip 128450 USB 2.0 Display Adapter DELOCK USB 2.0 to DVI/VGA/HDMI Adapter The second one looks pretty cool, but it says that Windows is a system requirement or what, so I'm not sure if it will work with mac os x? So how did you connected multiple monitors to you mac, and are these adapters the best choices, if yes then is there an OS independent one?

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• SSD for Visual studio : Intel X25-m G2 or OCZ Vertex

  - by meska

  hi, looking for laptop upgrade, and thinking about SSD drive. Laptop would be Dell Studio XPS with T9400 as i can get one for a very good price. So i was thinking about replacing the built in 500 GB hdd with some kind of SDD Currently two choices: OCZ Vertex Series 60 GB vs. Intel X25-M G2 MLC 80 GB Price is almost the same. From anandtech Intel performs badly in sequential write, but scores very high numbers in random write and random read (good for visual studio?) and i get more space. What do you think? OCZ Vertex or Intel X25-M G2 ? Purely from Visual Studio 2008 and upcoming 2010 perspective?

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• Single/Mulitple LUN for vmware vm hosting

  - by Yucong Sun

  I'm building a iscsi storage system for hosting about ~500 Vmware vm running concurrently. And I have a disk array with 15 disks, I only need moderate write performance but preferably not SPOFed. so, that leaves me with RAID1 / RAID10 , I have couple choices: 1) 3x LUN 4disk RAID10 + 3 hot-swap 2) 1x LUN 14disk RAID10 + 1 hot-swap 3) 7x LUN 2disk RAID1 + 1 host-swap Which way is better? Is there a real problem running 500 vms on single LUN? and would it be better to resort to 7 LUns so each VM is better isolated with each other?

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• Choosing a very basic Linux distro with minimal boot time?

  - by user30961

  I've had Ubuntu for a year now, like it but it doesn't match my needed configuration for my old laptop. So... I am using Linux mainly for webapps so I don't care much about user interface. What I need is a distro which is small enough to install on a SD memory card (or USB) since I am removing the hard drive, all my data is in the cloud. I also want it to have as short boot time as possible. I tried Puppy Linux and it seems ok but it had preinstalled looots af small apps I don't need, I would really like to have a distro with minimal preinstallations and add them on my own. So what are my choices and why would you recommend these?

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• NIC models for HVM guests in Xen 4.0

  - by Jed Daniels

  Is there a list of NIC models that I should use with various HVM guests in Xen 4.0? Is there even a list of possible choices for the model=field? I'm planning on running both Windows and FreeBSD guests on the particular Xen box that I'm configuring now, and ideally I'd like a setting that can work on both of them and get me gigabit speeds without a lot of extra hassle loading special drivers (similar to VMware's e1000 NIC option). Any suggestions? The vif line I'm currently using in my config is: vif = [ 'type=ioemu,bridge=eth0,model=ne2k_pci,script=vif-ovs' ] This works in my Windows XP SP3 VM, but is only recognized as a 10Mbit interface. Changing to model=e1000 or model=i82557b resulted in Windows not being able to find a driver for the NIC.

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• Best alternatives to recover lost directories in FAT32 external hard drive?

  - by Sergio

  Hi: I have an 320 GB ADATA CH91 external hard drive. I guess it has some problems with the connector of the USB jack. The point is that in certain occasions it fails in write operations generating data losses. Right now I lost a directory with several GB's of very useful information. Since then I have not attempted to write to the disk any more. What tool would you recommend to recover the lost data? The disk is FAT32 formatted (only one partition) and I use both Linux and Windows. What filesystem format would you recommend to avoid future data losses? I currently only use this external hard drive in Linux so there are several available choices (FAT, NTFS, ext3, ext4, reiser, etc.). Regards, Sergio

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• RAID driver to choose for slipstreaming XP installation on ASUS P5S800

  - by alex

  I'm trying to install Windows XP on my new SATA drive but I need to first slipstream the drivers with nLite. I've done this before, but not on an ASUS P5S800 - VM motherboard. I'm not used to the number of choices it gives me for drivers in SiS chipsets. When I look through the folder that I downloaded from ASUS for the RAID driver, I see many folders with different versions of the driver. Here are the folders or versions given. 180ob 964_180 965 966_968 What drivers do I need to add in order to get XP on my SATA disk?

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• Do the amount of CUDA cores matter for Sony Vegas

  - by Saif Bechan

  I am building a new PC, and I am wondering if I am making the right choices. The PC will mainly be used for video editing, and mainly in Sony Vegas. Now I have the choice of going with a video that that has more of less CUDO cores. To be precise I am choosing between a Ti and non-Ti version of an nVidea video card. Now I have read that sony vegas can partially use the CUDA cores to it's benefit, but not that much, and only if you use GPU acceleration. On the other hand I have heard it's better to leave GPU acceleration off as it will effect the quality of the output. Making it so that the CUDA cores actually don't make much of a difference after all.

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• How to dismiss the Windows 8.1 Upgrade banner?

  - by user81430

  As of today, my Windows 8 system is displaying a large banner covering about a quarter of the screen, demanding that I upgrade to Windows 8.1 for free. The banner helpfully informs me that that I can continue to use the computer while the upgrade is downloading. There's a button to go to the store for the upgrade, but no other choices, such as No Thanks, Maybe Later, or Absolutely Not. I can't find a way to dismiss the banner, and I can start programs but can't give them focus while the banner is present. So I'm dead in the water. How can I fix this? Bringing up Task Manager doesn't give me any options. My employer doesn't yet support Windows 8.1 (which is also an issue, but beyond my control) so I won't be able to connect to work if install the upgrade. So there is no way on God's green earth that I'm going to install this upgrade now.

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• powertop keeps telling me to turn off the same thing, over and over

  - by Rory McCann

  I am running an ubuntu lucid laptop on battery. I want to make my power last as long as possible. Aswell as the normal things like turn down screen brightness, and turn off wifi, I'm using powertop. It will sometimes tell me things, e.g.: Suggestion: Enable USB autosuspend by pressing the U key OK, I press the U key to do that. However a few minutes later it will give me the same suggestion, it's as if it never enabled USB autosuspend the first time. It does this for other things aswell, not just USB autosuspend. e.g. it'll give me this message frequently: An audio device is active 100.0% of the time: hwC0D1 LSI ID 1040 Q - Quit R - Refresh A - Turn HD audio powersave on Is there anything I can do to make these choices 'stick'? Or do I have some unfortunatle hardware that won't obey linux? (If so, is there any way to confirm this?)

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• Cisco FC SAN switch decision

  - by Chopper3

  I've got to buy a bunch of FC SAN switches in the next week or so, I have to, and want to, buy Cisco MDSs. Servers are HP BL490c G6's in C7000 chassis with Virtual-Connect Flex-10 ethernet interconnects and VC FC interconnects (Emulex HBAs btw), all running ESX 3.5U4 (for now). I think I've only really got two choices; MDS 9509's with dual-supervisors with a single 48-port 4Gb FC card MDS 9222i's with single supervisor and the built-in 18-FC-port/4-GigE-FCIP-port option Both have the same functionality (I think, buying the enterprise licence btw), both have plenty enough performance and adequate ports for now and the next three years. The 9222i's are about 55% the price of the 9509's - logic says get the 'i's but will I really miss the dual-supervisors? I've got lots of 9509's with dual-supervisors that I'm very happy with but I'm not sure I've every benefitted from the dual-sups in the past and they are nearly twice the price - but if I don't buy them and miss them I can't retrofit them later. What are your thoughts?

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• Two internet connections coming in, one Sonicwall Tz170 (enhanced os), and slow speed

  - by Development 4.0

  I work a lot from my home office and being in general a tad paranoid I have cable and DSL pipes coming into my house. I have used an Ebay bought Sonicwall Tz170 with the enhanced OS for a good while. I believe it does failover and has a feature for doing round robin on which connection is used. I get the impression from using it that I might not be getting the most out of this setup. Is it possible/likely that my router could be a cause of the slowdown? Are there more appropriate choices?

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• Database server: Small quick RAM or large slow RAM?

  - by Josh Smeaton

  We are currently designing our new database servers, and have come up with a trade off I'm not entirely sure of how to answer. These are our options: 48GB 1333MHz, or 96GB 1066MHz. My thinking is that RAM should be plentiful for a Database Server (we have plenty and plenty of data, and some very large queries) rather than as quick as it could be. Apparently we can't get 16GB chips at 1333MHz, hence the choices above. So, should we get lots of slower RAM, or less faster RAM? Extra Info: Number of DIMM Slots Available: 6 Servers: Dell Blades CPU: 6 core (only single socket due to Oracle licensing).

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• Mozilla Thunderbird 3.0.10: Messages are being sent back to me

  - by punkinette64

  When I send an email and I get a response, more often than not, in the To: is my email address. However, my email address also ends up in the From: column.The reply-from address is nowhere to be found;so I don't have any address with which I can send my reply, as both of them have just my email address. What am I doing wrong here? Is there some set-up in my Tools Options which is incorrect? The set-up in Options is pretty difficult to understand and it doesn't offer any to or reply-from choices. This is critical because I just cannot answer my emails because there is no one I can send a reply to.

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• Super-silent (mid tower) case and fan combo

  - by Dennis G.

  I want to build a HTPC for music/video/blu-ray playback (no gaming). I don't need an expensive HTPC case but just want to go with a standard medium tower case. However, I want it to be super silent so it doesn't make any annoying fan/disk noises when I watch movies. Ideally, it shouldn't make any noticeable noise at all. I understand that choosing a board, CPU and graphic card that run cool and don't consume a lot of power is important for designing a quiet machine, and I think I got that covered. However, there are so many choices in regards to cases, fans and power supplies that it's hard to get started. What are your recommendations for a case/fan (cpu+case)/power supply combination that run absolutely silent and can cool a standard Intel system with a low-power (possibly passively cooled) graphic card? I'm usually a fan of Antec cases, would an Antec Mini P180 be a good starting point? If so, which case fans, CPU fan and power supply would you recommend?

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• Where can I find the Sync Key in Firefox?

  - by tim11g

  I want to add other computers to a sync account with Firefox 12 (Windows) In the Firefox support pages, procedures are given for accessing the "Sync Key" and the "Recovery Key": At the top of the Firefox window, click on the Tools menu and select Options. Select the Sync panel. Click Manage Account and then select My Sync Key. Find Sync Key In Firefox 12 under Windows, The "Manage Account" menu on the Sync options dialog has only these choices: View Quota Change Password My Recovery Key Reset Sync Where has the "Sync Key" moved to? Or how is the Sync Key accessed?

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• Windows shuts down unexpectedly when waking up from sleep

  - by Kush

  I've been facing this issue since yesterday, whenever I put the computer into sleep mode and when I wake up, it takes me to boot menu with choices; start Windows normally, safe mode, etc. in short, it shuts down unexpectedly while waking up. I have my laptop dual booted with up-to-date Windows 7 SP1 (32-bit) and Ubuntu 10.10. This problem is not happening with Ubuntu. I googled the issue and went through this, this and this page. But, none of the threads were helpful to solve it. I've found that there's something to do with device drivers. What can be done to resolve the issue? Can SFC utility solve it if it is due to corrupt system files?

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