grep hogs entire cpu Post: 302591037

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Special Forums UNIX and Linux Applications grep hogs entire cpu Post 302591037 by Corona688 on Wednesday 18th of January 2012 11:19:39 AM

01-18-2012

Registered User

Server distributions often lower the tick rate so pre-emption happens less often, but it'd be ridiculous to turn it off. Anyone who's ever used windows 3.1 knows the consequences of that, and allowing one faulty usermode process to bomb your system is beyond stupid. I don't accept that option means what you think it does. I'll investigate in more detail myself.

There's an enormous problem with your explanation, anyway. His system did, in fact, pre-empt grep. How else could he have regained control by ctrl-alt-f1? Why would it pre-empt for ctrl-alt-f1, and not for the GUI? His system wasn't hardlocked. The GUI had malfunctioned.

---------- Post updated at 10:19 AM ---------- Previous update was at 08:51 AM ----------

I'm pretty sure you're talking about kernel-mode pre-emption, which is something different. It allows the kernel to pre-empt itself in some circumstances so it can respond more quickly and smoothly to realtime requests. This is often left disabled for servers, because it may trade some performance for response time.

This has nothing to do with the pre-emption of user-mode programs. A linux system that lacks user-mode pre-emption would not be stable or sane.

So I stand by my earlier point: grep should not have been able to freeze a system by consuming 100% CPU. Something else is going wrong with this system. If this is the system I think it is, COKEDUDE has had strange problems with this system before, like random segmentation faults in perfectly good programs, so I don't trust that grep itself is the issue.

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curlopt_pre_proxy

CURLOPT_PRE_PROXY(3)					     curl_easy_setopt options					      CURLOPT_PRE_PROXY(3)

NAME

       CURLOPT_PRE_PROXY - set pre-proxy to use

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);

DESCRIPTION

       Set  the  preproxy  to  use for the upcoming request. The parameter should be a char * to a zero terminated string holding the host name or
       dotted numerical IP address. A numerical IPv6 address must be written within [brackets].

       To specify port number in this string, append :[port] to the end of the host name. The proxy's port number may optionally be specified with
       the separate option CURLOPT_PROXYPORT(3). If not specified, libcurl will default to using port 1080 for proxies.

       A  pre  proxy is a SOCKS proxy that curl connects to before it connects to the HTTP(S) proxy specified in the CURLOPT_PROXY option. The pre
       proxy can only be a SOCKS proxy.

       The pre proxy string should be prefixed with [scheme]:// to specify which kind of socks is used. Use socks4://,	socks4a://,  socks5://	or
       socks5h://  (the  last  one  to	enable	socks5	and asking the proxy to do the resolving, also known as CURLPROXY_SOCKS5_HOSTNAME type) to
       request the specific SOCKS version to be used. Otherwise SOCKS4 is used as default.

       Setting the pre proxy string to "" (an empty string) will explicitly disable the use of a pre proxy.

       The application does not have to keep the string around after setting this option.

DEFAULT

       Default is NULL, meaning no pre proxy is used.

       When you set a host name to use, do not assume that there's any particular single port number used widely for proxies. Specify it!

PROTOCOLS

       All except file://. Note that some protocols don't do very well over proxy.

EXAMPLE

       TODO

AVAILABILITY

       Added in 7.52.0

RETURN VALUE

       Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.

SEE ALSO

       CURLOPT_PROXY(3), CURLOPT_HTTPPROXYTUNNEL(3),

libcurl 7.54.0							 December 21, 2016					      CURLOPT_PRE_PROXY(3)