From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id B621B62EB3 for ; Wed, 23 Feb 2022 10:21:19 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id B107F2C383 for ; Wed, 23 Feb 2022 10:20:49 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 14F372C378 for ; Wed, 23 Feb 2022 10:20:49 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id E7BD946342 for ; Wed, 23 Feb 2022 10:20:48 +0100 (CET) Message-ID: Date: Wed, 23 Feb 2022 10:20:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:98.0) Gecko/20100101 Thunderbird/98.0 Content-Language: en-US To: Proxmox Backup Server development discussion , Dominik Csapak References: <20220217094041.1632033-1-d.csapak@proxmox.com> <20220217094041.1632033-6-d.csapak@proxmox.com> From: Thomas Lamprecht In-Reply-To: <20220217094041.1632033-6-d.csapak@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.058 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record T_SCC_BODY_TEXT_LINE -0.01 - Subject: Re: [pbs-devel] [RFC PATCH proxmox-backup 1/3] proxmox-rest-server: OutputFormatter: add new format_data_streaming method X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Feb 2022 09:21:19 -0000 On 17.02.22 10:40, Dominik Csapak wrote: > +fn start_data_streaming(value: Value, data: Box) -> tokio::sync::mpsc::Receiver, Error>> { > + let (writer, reader) = tokio::sync::mpsc::channel(1); > + > + std::thread::spawn(move || { just for the record, spawning a separate thread for every request isn't a good idea performance wise, while the cost is lower than say forking, its still non-negligible and a few users having the gui open will result in hundreds of threads spawned per minute; iow. system threads should only be spawned for long running (as in about as long running as the whole programs lifetime) tasks, not for one-time short lived tasks with a definite purpose. Using tokio's spawn_blocking is nicer for such things as while it also may spawn a thread it lets the thread idle for 10s after last task completion to wait for new work before exiting again. Having a PBS web interface dashboard open shows ~8 XHR request in 10s, so it's quite likely that we'd only ever have one such thread reused constantly per user-session, reducing costs a lot. btw., as it was questioned during off-list talk: block_in_place makes only then sense for blocking code if spawn_blocking cannot be used due to missing Send + 'static guarantees on the fn to call. > + let output = proxmox_async::blocking::SenderWriter::from_sender(writer); > + let mut output = std::io::BufWriter::new(output); > + let mut serializer = serde_json::Serializer::new(&mut output); > + let _ = data.sender_serialize(&mut serializer, value); > + }); > + > + reader > +} > +