Resource Limits


The following urlcp settings control resources used by the fetch functions, such as time, size, memory and files:

  • maxframes (integer) Sets the maximum number of subsidiary frames, iframes, and/or JavaScript pages (<SCRIPT SRC=...></SCRIPT> to also fetch for a document. The default is 5. Frames are only fetched if getframes is on, <IFRAME>s only if getiframes is on, and JavaScript pages are only fetched if javascript and getscripts are on.

  • maxhdrsize (integer) The maximum size of headers allowed; when exceeded a "Max headers size exceeded (truncated)" message is generated. The default is 128K; -1 indicates no limit. It is rarely necessary to increase this limit, as headers are small and mostly fixed in size. Added in version 2.6.937800000 19990920; was part of maxpgsize in prior versions. In version 4.01.1023500000 20020607 and later the previous setting is returned. Aka maxhdrsz, maxheadersize, maxheadersz.

  • maxconnidletime (double) Maximum idle time in seconds (unused time between requests) that a connection may be opened before it is closed and not reused for Keep-Alive. The default is 5. Added in version 5.00.1094074734 20040901. Returns previous setting.

  • maxconnlifetime (double) Maximum seconds of real time that a connection can be open and still be re-used with Keep-Alive for future requests. Idle connections that are older than this will be closed. Defaults to 600 (i.e. 10 minutes). Added in version 5.00.1096313795 20040927. Returns previous setting.

  • maxdownloadsize (integer) Sets the maximum download size (network transfer size) of a response document body. -1 indicates no limit, and is the default. Maximum download size is checked before content and transfer encodings are decoded, i.e. it is a limit on network transfer size, not final document size (which the maxpgsize setting controls). A network transfer that exceeds maxdownloadsize will generate a "Max download size exceeded (truncated)" error message, and the transfer will be aborted. Added in version 5.01.1249039000 20090731. Aka maxdownloadsz.

    Note that since encodings are decoded on-the-fly as the document is downloaded, not only will exceeding maxdownloadsize abort the transfer, but typically so will exceeding maxpgsize - though possibly at an earlier point, if a compression encoding was used. This is why maxdownloadsize can usually be left at its -1 (unlimited) default, and just maxpgsize set instead: the latter setting controls final doc size, and indirectly sets an upper limit for network transfer bandwidth. Thus both memory and network usage can be limited with maxpgsize.

  • maxidleconn (integer) Maximum number of idle connections to cache for future Keep-Alive requests. Added in version 5.1, where the default is 2. Returns previous setting.

  • maxkeepaliverequests or maxconnrequests (integer)

    Sets the maximum number of page requests to do on a single Keep-Alive connection, before closing the connection and re-opening a new one. -1 sets no limit. Added in version 4.04.1068090000 20031105, where the default was 0, and Keep-Alive was only supported if <urlcp netmode sys> was set. In version 5.1, the default is 100, and Keep-Alive is supported for normal <urlcp netmode int> fetches as well. Setting 1 (or 0) turns off Keep-Alive, i.e. all requests send a Connection: close header and only one request per connection is used. Note that a value of 3 or more is needed for NTLM authentication (Integrated Windows Authentication) to function. Returns previous setting.

  • maxpgcachesz or maxpagecachesz or maxpgcachesize or maxpagecachesize or pagecachesz (integer) Maximum page cache size in bytes. Only indirect pages are cached (e.g. frames, iframes, scripts), not directly <fetch>ed pages. Default is 5MB. Suffixes KB, MB, GB may be given, e.g. "5MB". Returns previous setting. Added in version 5.00.1096313795 20040927.

  • maxpgsize (integer) Sets the maximum page size that will be accepted for a document. Documents that are longer will be truncated and generate a "Max page size exceeded (truncated)" message. The default is 512KB; a setting of -1 indicates no limit. In versions prior to 2.6.937800000 19990920, the default was 100KB, the size of any headers was included, and -1 was not permitted. In version 4.01.1023500000 20020607 and later the previous setting is returned. Aka maxpagesize, maxpagesz, maxpgsz.

    The maximum page size is checked after all content and/or transfer encodings (if any) are decoded; i.e. it controls the size of the final document returned by <fetch>. Since encodings are decoded on-the-fly as the document is downloaded, reaching maxpgsize will also typically abort the network transfer as well. See also the maxdownloadsize setting for limiting network document size directly (though setting maxpgsize is typically enough).

  • maxprotspacecachesz or maxprotspacecachesize (integer) Maximum protection space cache size in bytes. The protection space cache is used to determine which URLs are protected with what user/pass credentials, so that later fetches to the same space do not need to negotiate credentials (and waste transactions). Defaults to 128KB. Suffixes KB, MB, GB may be given, e.g. "5MB". Returns previous setting. Added in version 5.1.

  • maxprotspaceidletime (integer)

    Maximum idle time of a protection space in the cache, in seconds. After this amount of time in disuse, the protection space will be deleted, which means future fetches may have to re-negotiate credentials. Defaults to 3600 (i.e. 1 hour); -1 is unlimited. Returns previous setting. Added in version 7.06.1465935000 20160614.

  • maxprotspacelifetime (integer)

    Maximum lifetime of a protection space in the cache, in seconds. After this amount of time since its creation, the protection space will be deleted, which means future fetches may have to re-negotiate credentials. Defaults to -1 (unlimited). Returns previous setting. Added in version 5.1. Prior to version 7.06.1465935000 20160614, the default was 3600 (one hour).

  • maxredirs (integer) Sets the maximum number of redirects that will be followed per URL fetch. Exceeding this limit generates the message "Too many redirections (N) while fetching ...". The limit may be 0 to disallow redirects altogether. The default maxredirs value is 5.

  • pacfetchretrydelay (integer)  

    Sets the time in seconds before retrying a failed proxy pacurl fetch (here), if enabled. Because all URLs fetched depend on the proxy auto-config script, all <fetch>es would keep attempting to re-fetch the same PAC URL if it fails. Thus, to reduce the load on the PAC URL server, the PAC script will not be re-fetched after error for pacfetchretrydelay seconds. The default is 10; a negative value means infinite (never retry automatically). Changing the pacurl will clear the last-try timestamp and allow a re-fetch to occur. Added in version 7.05.

  • proxyretrydelay (integer)  

    Sets the time in seconds before retrying a proxy when other proxies are available. When proxy auto-config is enabled (here), it is possible that the FindProxyForURL() PAC function may return more than one proxy for a given URL: these proxies are normally tried in the order returned, until one succeeds. However, a "bad" (e.g. unresponsive) proxy is flagged in the proxy cache: every subsequent <fetch>'s FindProxyForURL()-returned list will be altered to have such bad proxies moved to the end of the list. This deprecation lasts proxyretrydelay seconds (or until the proxy succeeds).

    This allows successive <fetch>es to dynamically adapt to unresponsive proxies, even when the FindProxyForURL() list may be constant or unaware of the proxy's unresponsiveness. For example, if FindProxyForURL() always returns "PROXY; PROXY", once the proxy detectably fails, future fetches will try first, for up to proxyretrydelay seconds, instead of waiting for to fail first.

    However, if FindProxyForURL() always returns just "PROXY", that proxy will alway be tried, even after failure: there is no other proxy offered to try.

    The proxyretrydelay setting was added in version 7.05, and defaults to 300. Negative values mean infinite, i.e. never automatically retry a bad proxy (when others are offered). The internal cache of bad proxies may be cleared with the clearproxycache option (here).

  • savedownloaddoc (boolean) Whether to save the network-transferred download doc, if it varies from the final (after content/transfer encodings decoded) document. The default is off to save memory, since the decoded document is usually more useful. Added in version 5.01.1249203000 20090802.

  • scriptmaxtimer (integer)   Sets maximum time (in seconds) to run JavaScript timers (set by setInterval() and setTimeout(). This represents a compromise between the dynamic JavaScript environment and the static return value of the fetch lib. The default is 3 seconds, which is less than the scripttimeout and allows some timers to run, but doesn't wait indefinitely for an infinitely-recurring setInterval(). A value of -1 means no limit (but scripttimeout still applies). Returns previous value. Added in version 4.03.1050609000 20030417. See also scriptrealtimers (here).

  • scriptmem (integer/size) Controls how much memory (in bytes) to allow the JavaScript engine to allocate when running JavaScript code. Exceeding this limit may generate an error such as "JavaScript exceeded scriptmem limit". This helps prevent erroneous JavaScript pages from consuming all available memory, e.g. if there is an infinite JavaScript loop. Standard memory size suffixes such as MB or KB may be appended to the integer value for clarity. The default value is 20MB. Note that a very low limit may cause problems even for pages with no JavaScript, as some JavaScript library objects must be allocated for every page; a minimum value of several MB is recommended. Returns previous setting. Added in version 4.01.1023500000 20020607.

  • scriptgcthreshold (integer/size/percentage)

    Sets the threshold of scriptmem usage that the JavaScript engine should begin garbage collection. Can be a percentage (e.g. the default of "75%"), or an absolute integer/size (e.g. "15MB"). Added in version 7.06.1490209000 20170322.

  • scripttimeout (integer) Controls how much total time (in seconds) to allow JavaScript code to execute on a page. Exceeding this limit will generate a " Timeout: JavaScript exceeded scripttimeout" message. This helps prevent an infinite loop in JavaScript from consuming all CPU and hanging the process. Note that this is a limit for the total time consumed by a page's JavaScript, not per <SCRIPT> block. This timeout also applies after the page has been fetched, so it need not be smaller than the page timeout. The default is 5 seconds. -1 indicates no limit. Returns previous setting. Added in version 4.01.1023500000 20020607. Do not confuse this setting with the Vortex script timeout (here), nor the fetch timeout (below).

  • timeout (integer)

    Sets the per-fetch timeout, in seconds. A document fetch that takes longer than the timeout is aborted, the data read so far (if any) is returned, and an error message is issued (may be captured via putmsg, here). The default is 30 seconds. This timeout applies to nslookup, and to each URL fetched by fetch and submit, so a framed document or one with <SCRIPT SRC=...> links, redirects etc. may take longer. Do not confuse this setting with the Vortex script timeout (here), nor the JavaScript timeout scripttimeout (above).

  • writebuffersize (integer) Sets the initial buffer size to use for some writes, e.g. for writing <submit TOFILE> documents to disk, or decoding content/transfer encodings. The default is 32KB. Some write buffers may increase past this limit if needed. Added in version 5.01.1249039000 20090731. Returns previous buffer size.

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