<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 13 Jun 2015, at 21:35, Ingela Andin <<a href="mailto:ingela.andin@gmail.com" class="">ingela.andin@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Creating a name for the profile is not that heavy?! The ets-table is an implementation detail not written in stone, it could use some other data structure like a dict or something. Feel free make a PR, if you make a good case it can be changed.</div></div></blockquote><br class=""></div><div>Creating an ets table really isn’t a heavy operation.</div><div><br class=""></div><div>Consider the following program:</div><div><br class=""></div><div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">-module(etsc).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">-compile(export_all).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; font-family: Menlo; min-height: 13px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">t(N) when N > 0 -></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class=""> T = ets:new(t, []),</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class=""> ets:delete(T),</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class=""> t(N-1);</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">t(_) -></div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class=""> ok.</div><div class=""><br class=""></div></div><div><br class=""></div><div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">Eshell V5.10.4 (abort with ^G)</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">1> c(etsc).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">{ok,etsc}</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">2> timer:tc(etsc,t,[1000]).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">{2775,ok}</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">3> timer:tc(etsc,t,[1000]).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">{2612,ok}</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">4> timer:tc(etsc,t,[1000]).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">{2055,ok}</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">5> timer:tc(etsc,t,[1000]).</div><div style="margin: 0px; font-size: 11px; font-family: Menlo;" class="">{1881,ok}</div><div class=""><br class=""></div></div>That is, on my old Macbook Air, it takes about a microsecond to create an ets table*.<div class=""><br class=""></div><div class="">Creating an atom is also obviously cheap, but I cringe a bit when list_to_atom/1 is used in generic code - although in this particular case, I guess creating memory leaks because of it is not very likely.</div><div class=""><br class=""></div><div class="">BR,</div><div class="">Ulf W</div><div class=""><br class=""></div><div class="">* Obviously, this test doesn’t accumulate ets tables. I removed the ets:delete/1 call, and things looked much worse:</div><div class="">- Creating the first 1000 tables took ca 13 ms.</div><div class="">- Creating 1000 tables when there were already 67K tables, took 6.2 seconds.</div><div class="">- However, creating an ets table from another process was still pretty fast - ca 10 usec</div><div class="">I conclude that having thousands of ets tables owned by a single process is a *bad* idea (probably not for this reason alone).</div><div class=""><br class=""><div apple-content-edited="true" class="">
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><div class=""><div class="">Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.</div><div class=""><a href="http://feuerlabs.com" class="">http://feuerlabs.com</a></div></div><div class=""><br class=""></div></span><br class="Apple-interchange-newline">
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