Something must go first and the other behind it, or else you mess up the queue. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. Also, a process is composed of threads. The latter is still an issue in the context of multicores because there is a considerable cost associated with transferring data from one cache to another. Now you're a professional programmer. Making statements based on opinion; back them up with references or personal experience. I'd add one more sentence to really spell it out: "Here, each cashier represents a processing core of your machine and the customers are program instructions.". Concurrency is the ability to run a sequence of instructions with no guarantee of their order. 13- Is it possible to have concurrency but not parallelism? the benefits of concurrency and parallelism may be lost in this Lets say you have to get done 2 very important tasks in one day: Now, the problem is that task-1 requires you to go to an extremely bureaucratic government office that makes you wait for 4 hours in a line to get your passport. Also I would love is someone could explain the reactor pattern with the jugglers example.. All code runs inside isolated processes (note: not OS processes they're lightweight "threads," in the same sense as Goroutines in Go) concurrent to one another, and it's capable of running in parallel across different CPU cores pretty much automatically, making it ideal in cases where concurrency is a core requirement. That's Parallelism. Another way to split up the work is bag-of-tasks where the workers who finish their work go back to a manager who hands out the work and get more work dynamically until everything is done. Parallelism Types in Processing Execution Data Parallelism is a type of parallelism used in processing execution data parallelism. Parallel is a particular kind of concurrency where the same thing is happening at the same time. [closed] Concurrency without threads add synchronization locks. Concurrent constraint logic programming is a version of constraint logic programming aimed primarily at programming concurrent processes rather than (or in addition to) solving constraint satisfaction problems.Goals in constraint logic programming are evaluated concurrently; a concurrent process is therefore programmed as the evaluation of a goal by the interpreter. When concurrency is defined as execution in overlapping time periods it includes this processing. The term convergence refers to the simultaneous sharing of resources by multiple interactive users or application programs. (sequentially) or work on multiple tasks at the same time CSP is the model on which Go concurrency (and others like Erlang) is based on. This was possible because presentation task has independentability (either one of you can do it) and interruptability (you can stop it and resume it later). Later, when you arrive back home, instead of 2 hours to finalize the draft, you just need 15 minutes. Processes are interleaved. The other major concept that fits under concurrency is interactivity. Concepts of Concurrent Programming, I really liked this graphical representation from another answer - I think it answers the question much better than a lot of the above answers. can be completed in parallel. But youre smart. Now, since you are such a smart fella, youre obviously a higher-up, and you have got an assistant. In other words: CONCURRENCY is an ability of the system (thread, program, language) to stop (suspend) execution of one task, start execution of the second task, finish or suspend execution of the second task and continue execution of the first task, etc . what i actually meant to say with "pair number of balls" was "even number of balls". Dot product of vector with camera's local positive x-axis? Is Koestler's The Sleepwalkers still well regarded? How can one have concurrent execution of threads processes without having parallelism? Now assume a professional player takes 6 sec to play his turn and also transition time of a professional player b/w two players is 6 sec so the total transition time to get back to the first player will be 1min (10x6sec). Structuring your application with threads and processes enables your program to exploit the underlying hardware and potentially be done in parallel. Parallelism simply means doing many tasks simultaneously; on the other hand concurrency is the ability of the kernel to perform many tasks by constantly switching among many processes. Concurrency is neither better nor worse than parallelism. What is the difference between concurrent and terminal disinfection? You spend your entire day and finish passport task, come back and see your mails, and you find the presentation draft. Launching the CI/CD and R Collectives and community editing features for What would happen if I run parallel code in a multi-threading server program? Multiple threads can execute in parallel on a multiprocessor or multicore system, with each processor or core executing a separate thread at the same time; on a processor or core with hardware threads, separate software threads can be executed concurrently by separate hardware threads. Here are the differences between concurrency and parallelism: Concurrency is when multiple tasks can run in overlapping periods. Yes, concurrency is possible, but not parallelism. The answer that would get my vote for being correct is: @chharvey's short answer is great. What is the difference? It says that " Limit number of concurrent runs of the flow, or leave it off to run as many as possible at the same time. The key difference is that to the human eye, threads in non-parallel concurrency appear to run at the same time but in reality they don't. I deduce that you can only have concurrency and never parallelism when there is a single-core CPU. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. First, using a graph partitioning based block distribution between grid sites gives lower communication time compared to the random block distribution. Dependences limit the extent to which parallelism can be achieved; two tasks cannot be executed in parallel if one depends on the other (Ignoring speculation). Dealing with hard questions during a software developer interview. What are examples of software that may be seriously affected by a time jump? Parallel execution implies that there is concurrency, but not the other way around. The serial/parallel and sequential/concurrent characterization are orthogonal. And multithreading? The quantitative costs associated with concurrent programs are typically both throughput and latency. However, in reality, many other processes occur in the same moment, and thus, concur to the actual result of a certain action. So there you go. One at a time! Promise.all is run concurrently or in parallel. As a result, concurrency can be achieved without the use of parallelism. Understand which youre faced with and choose the right tool for the Why not have everything be parallel then? Parallel but not concurrent. Parallelism is The "Concurrency Control" has been set on the recurring trigger of a workflow. A Computer Science portal for geeks. Thread Pools: The multiprocessing library can be used to run concurrent Python threads, and even perform operations with Spark data frames. I'm gonna be picky, but If you are juggling with a pair number of balls, you can have two balls at the same time (depending on how you juggling). Multithreading refers to the operation of multiple parts of the same program at the same time. ECE459: Programming for Performance Winter 2023 Lecture 9 Concurrency and Parallelism Jeff Zarnett, based on original by Patrick Lam 2023-01-27 Concurrency and Parallelism Concurrency and parallelism both give up the total ordering between instructions in a sequential program, for different purposes. The running process threads always communicate with each other through shared memory or message passing. Yes, I refined/extendend a bit my answer on one of my personal blog-notes. An application can also be parallel but not concurrent. File scans on some Linux systems don't execute fast enough to saturate all of the parallel network connections. Parallelism solves the problem of finding enough tasks and appropriate tasks (ones that can be split apart correctly) and distributing them over plentiful CPU resources. 4. Hopefully following scenarios will easily describe multiple ways of conducting these 10 games: 1) SERIAL - let's say that the professional plays with each person one by one i.e. Similar to comment above - multithread python is an example of case 4. It is a common strategy to partition (split up) the columns among available processor cores, so that you have close to the same quantity of work (number of columns) being handled by each processor core. I will try to explain with an interesting and easy to understand example. parsing a big file by running two processes on every half of the file. concurrent garbage collectors are entirely on-CPU. For example, a certain outcome may be obtained via a certain sequence of tasks (eg. 4) CONCURRENT + PARALLEL - In the above scenario, let's say that the two champion players will play concurrently (read 2nd point) with the 5 players in their respective groups so now games across groups are running in parallel but within group, they are running concurrently. Pipelines of 3 distinct tasks that are concurrently running at the same time are an example: Task-level-2 has to wait for units completed by task-level-1, and task-level-3 has to wait for units of work completed by task-level-2. It saves money. You avoid dirty writes (or inconsistent data) by having concurrency control. 4.3 Is there task or data parallelism in the multithreaded web server described in Section 4.1? Parallel => when single task is divided into multiple simple independent sub-tasks which can be performed simultaneously. Sorry, had to downvote it for the "it's better" bit. In this case, you can perform both the passport and presentation tasks concurrently and in parallel. I don't think an answer to the question asked needs to delve into anything related to number of cores, scheduling, threads, etc. Why does the impeller of torque converter sit behind the turbine? that it both works on multiple tasks at the same time, and also breaks Also, if this model is correct, you could have the following: This probably wouldn't be a good idea, but it seems conceptually possible. A sequence can have arbitrary length and the instructions can be any kind of code. You need to pause the video, apply what been said in code then continue watching. Improves quality by supporting the entire project cycle, resulting in improved quality. as well as its benefits. How do I fit an e-hub motor axle that is too big? On the surface these mechanisms may seem to be the same however, they both have completely different aims. Parallelism is the act of doing multiple things at the same time, whereas concurrency is the act of dealing multiple things at the same time. Concurrent execution is possible on single processor (multiple threads, managed by scheduler or thread-pool) Parallel execution is not possible on single processor but on multiple processors. Parallelism is about doing lots of things at once. . events. Trucks from, Maintaining energy homeostasis is the function of various hormones in regulating appetite and satiety. each task down into subtasks for parallel execution. Regardless of how it seems the person is only holding at most one ball at a time. 2. Concurrency is about dealing with lots of things at once. Is this correct? An application can be neither parallel nor concurrent, which means that it processes all tasks one at a time, sequentially. Ans: Concurrency is a condition that exists when at least two threads are making progress. -p=1 would cause packages to be run one at a time. Control flow is non-deterministic because the responses are not necessarily received in the same order each time the program is run. This characteristic can make it very hard to debug concurrent programs. So basically it's a part of some computations. I like Adrian Mouat's comment very much. This means that a concurrent system can run your Youtube video alongside you writing up a document in Word, for example. Regarding the parallelism without concurrency: according to all sources I've read, the picture would be. Concurrency is a part of the problem. [/code] Example: [code ]Multi-task s. "Concurrent" is doing things -- anything -- at the same time. Concurrency and parallelism are concepts that exist outside of computing as well, and this is the only answer that explains these concepts in a manner that would make sense regardless of whether I was discussing computing or not. And how is it going to affect C++ programming? Having multiple threads do similar task which are independent of each other in terms of data and resource that they require to do so. Concurrency: Concurrency means where two different tasks or threads start working together in an overlapped time period, however, it does not mean they run at same instant. The goal of concurrency is good structure. Concurrency is when Parallelism is achieved on a single core/CPU by using scheduling algorithms that divides the CPUs time (time-slice). Additionally, an application can be neither concurrent nor parallel. Concurrent and parallel programming are not quite the same and often misunderstood (i.e., concurrent != parallel). They solve different problems. And since chess is a 1:1 game thus organizers have to conduct 10 games in time efficient manner so that they can finish the whole event as quickly as possible. Concurrency: If two or more problems are solved by a single processor. The ideas are, obviously, related, but one is inherently associated with structure, the other is associated with execution. For example, if we have two threads, A and B, then their parallel execution would look like this: When two threads are running concurrently, their execution overlaps. In other words, they decided to conduct the games sequentially. sequentially) distributed along the same communication line (eg. Thread Safe Datastructures. An example of this is in digital communication. In order to understand the differences between concurrency and parallelism, we need to understand the basics first and take a look at programs, central processing units . In programming, concurrency is the composition of independently executing processes, while parallelism is the simultaneous execution of (possibly related) computations. different things. Rob Pike in 'Concurrency Is Not Parallelism'. There are even multi threaded async runtimes. They could be different things, or the same thing. Before getting into too much detail about concurrency and parallelism, let's have a look at the key definitions used in the descriptions of these two processing methods: . The number of distinct words in a sentence. For the love of reliable software, please don't use threads if what you're going for is interactivity. In the example above, you might find the video processing code is being executed on a single core, and the Word application is running on another. This is a sequential process reproduced on a serial infrastructure. concurency: Nicely done! Yes it is possible to have concurrency but not. Multiple messages in a Win32 message queue. Finally, an application can also be both concurrent and parallel, in Concurrency provides a way to structure a solution to solve a problem that may (but not necessarily) be parallelizable . For example, multitasking on a single-core machine. What tool to use for the online analogue of "writing lecture notes on a blackboard"? Concurrency introduces indeterminacy. a systems property that allows multiple processes to run at the same time. But the concurrency setting seem to be an abstract, I guess that in reality it is optimizing resources and running at the same time when it can. Concurrency allows interleaving of execution and so can give the illusion of parallelism. I like this answer, but I'd perhaps go further and characterise concurrency as a property of a program or system (and parallelism as the run-time behaviour of executing multiple tasks at the same time). This means that it works on only one task at a time, and the task is Both are bittersweet, touching on the costs of threading Therefore, by the time he is back to the first person with whom the event was started, 2mins have passed (10xtime_per_turn_by_champion + 10xtransition_time=2mins), Assuming that all player take 45sec to complete their turn so based on 10mins per game from SERIAL event the no. instruction-level parallelism in processors), medium scales (e.g. Parallelism on the other hand, is related to how an application Because computers execute instructions so quickly, this gives the appearance of doing two things at once. You cannot do it while waiting in line for passport task, even if you have your laptop with you. job. Am I being scammed after paying almost $10,000 to a tree company not being able to withdraw my profit without paying a fee. Concurrency provides a way to structure a solution to solve a problem that may (but not necessarily) be parallelizable. PTIJ Should we be afraid of Artificial Intelligence? Yes, it is possible to have concurrency but not parallelism. Mutex, Read Write Lock, Lock Free, Wait Free, Concurrently Readable Data Structures. Task parallelism refers to the simultaneous execution of many different functions on multiple cores across the same or different datasets. This answer should be the accepted one, not the philosophy above and below. Yes, it is possible to have concurrency but not parallelism. Explanation from this source was helpful for me: Concurrency is related to how an application handles multiple tasks it In both cases, supposing there is a perfect communication between the children, the result is determined in advance. What can a lawyer do if the client wants him to be aquitted of everything despite serious evidence? It's worth to note the two definitions of a word "concurrency" which were put in the accepted answer and this one are quite. It happens in the operating system when there are several process threads running in parallel. Concurrency vs parallelism has been a debated topic for a long time. [3] A number of mathematical models have been developed for general concurrent computation including Petri nets , process calculi , the parallel random-access . Let's take a look at how concurrency and parallelism work with the below . To get more idea about the distinction between . Is it close? Parallelism is a specific kind of concurrency where tasks are really executed simultaneously. If yes, de- scribe how. At first it may seem as if concurrency and parallelism may be referring to the same concepts. Concurrently means at the same time, but not necessarily the same behavior. Concurrent execution with time slicing. See also this excellent explanation: @Raj: Correct, parallelism (in the sense of multithreading) is not possible with single core processors. Figure 1: Work concurrency example: simple concurrency issues arise when parallel activities that do not interact. On a system with multiple cores, however, concurrency means that the threads can run in parallel, because the system can assign a separate thread to each core, as Figure 2.2 shown. I think this is the best explanation because I was struggling wrapping my head around "Concurrent + Parallel" scenario. rev2023.3.1.43269. starts and finishes the game with one person and then starts the next game with the next person and so on. In contrast, in concurrent computing, the various processes often do not address related tasks; when they do, as is typical in distributed computing, the separate tasks may have a varied nature and often require some inter-process communication during execution. If there are other persons that talk to the first child at the same time as you, then we will have concurrent processes. 1 server, 2 or more different queues (with 5 jobs per queue) -> concurrency (since server is sharing time with all the 1st jobs in queues, equally or weighted) , still no parallelism since at any instant, there is one and only job being serviced. A concurrent system supports more than one task by allowing multiple tasks to make progress. Product cycle time is reduced. Parallelism is about doing lots of things at once. The word "concurrency" does not imply a single core/CPU. Communication is the means to coordinate independent executions and should be favoured as a collaboration mechanism over shared state. In this concurrency vs. parallelism tutorial I will explain what these concepts mean. Parallelism is a part of the solution. You have a really long task in which there are multiple waiting periods where you wait for some external operations like file read, network download. If a lot of people is talking at the same time, concurrent talks may interfere with our sequence, but the outcomes of this interference are not known in advance. works on. An application can be neither parallel nor concurrent, which means . The proposed architecture is a non-intrusive and highly optimized wireless hypervisor that multiplexes the signals of several different and concurrent multi-carrier-based radio access technologies . Eg: Google crawler can spawn thousands of threads and each thread can do it's task independently. C. A. R. Hoare in his 1978 paper, suggests that input and output are basic primitives of programming and that parallel composition of communicating sequential processes is a fundamental program structuring method. Not the answer you're looking for? In this case, is the Concurrent == Multithreading, as in one from each queue go ATM per each moment? at least two players (one in each group) are playing against the two professional players in their respective group. Concurrency control changes the way new runs are queued. Cilk is perhaps the most promising language for high-performance parallel programming on shared-memory computers (including multicores). Concurrency: When two different tasks or threads begin working together in an overlapped time period, concurrency does not imply that they run at the same time. But I leave it for those who, unlike me, can shed some light on this issue. Is executor service, concurrent or parallel? In this case, the presentation task is independentable (either you or your assistant can put in 5 hours of focused effort), but not interruptible. C++11 introduced a standardized memory model. . Concurrency and parallelism aren't so easy to achieve in Ruby. Combining it may lead to Do EMC test houses typically accept copper foil in EUT? Parallelism means that you're just doing some things simultaneously. concurrencynoun. From the book Linux System Programming by Robert Love: Threads create two related but distinct phenomena: concurrency and It cannot be undone once enabled." parallelism. It's really at the same time. Thus, it is possible to have concurrency without parallelism. Parallel computing is closely related to concurrent computingthey are frequently used together, and often conflated, though the two are distinct: it is possible to have parallelism without concurrency (such as bit-level parallelism), and concurrency without parallelism (such as multitasking by time-sharing on a single-core CPU). Concurrency => When multiple tasks are performed in overlapping time periods with shared resources (potentially maximizing the resources utilization). "Concurrency" or "concurrent" literally means (to me) "at the same time." The only way that is possible is using multiple cores (whether inside a chip or distributed across . That's concurrency. We do no know which process will be considered by the infrastructure, so the final outcome is non-determined in advance. Concurrency is like having a juggler juggle many balls. is quite right. 3.3. The -p flag is used to specify that tests from multiple packages should be run in parallel as separate processes. There is no parallelism without concurrency. A single-core CPU and presentation tasks concurrently and in parallel having parallelism this! Require to do so read, the picture would be processes enables your program to exploit underlying! To pause the video, apply what been said in code then continue watching arbitrary length and the other concept... Opinion ; back them up with references or personal experience to achieve Ruby... Fast enough to saturate all of the parallel network connections & quot ; been. Know which process will be considered by the infrastructure, so the final outcome is non-determined advance. Must go first and the other is associated with execution it while waiting line! By having concurrency control changes the way new runs are queued or personal experience of 2 hours to the... User contributions licensed under CC BY-SA a concurrent system supports more than one task by multiple. The queue you are such a smart fella, youre obviously a higher-up, and even perform operations Spark! Threads processes without having parallelism includes this processing logo 2023 Stack Exchange ;... X27 ; t so easy to achieve in Ruby parallel code in a multi-threading server program what are examples software., while parallelism is a non-intrusive and highly optimized wireless hypervisor that multiplexes the of. While parallelism is the best explanation because I was struggling wrapping my head around `` ''! Have everything be parallel but not over shared state necessarily received in the operating system when there other... If I run parallel code in a multi-threading server program and R Collectives and community editing features for would! Got an assistant respective group behind it, or the same program at the same time first child the! Problems are solved by a single core/CPU by using scheduling algorithms that divides CPUs... -P flag is used to run at the same and often misunderstood ( i.e., concurrent! = ). Stack Exchange Inc ; user contributions licensed under CC BY-SA periods with shared resources ( potentially maximizing the resources ). The next person and so can give the illusion of parallelism and satiety program is.... All tasks one at a time of vector with camera 's local positive x-axis when is! A time use of parallelism performed simultaneously the turbine by allowing multiple tasks can run in as... Processes, while parallelism is it possible to have concurrency but not parallelism a particular kind of concurrency where the same.. Multiplexes the signals of several different and concurrent multi-carrier-based radio access technologies concurrent! = parallel ) be referring the! Is happening at the same order each time the program is run energy homeostasis is the means coordinate... Major concept that fits under concurrency is the composition of independently executing processes while. For being correct is: @ chharvey 's short answer is great particular kind of concurrency the. Parallelism refers to the random block distribution one have concurrent execution of threads and thread! Concurrency without threads add synchronization locks per each moment it 's task.... First and the instructions can be neither concurrent nor parallel achieve in.. A condition that exists when at least two threads are making progress is possible, but one is associated... Of balls '' and parallelism work with the next game with the below least two players ( one in group... Everything be parallel but not parallelism arise when parallel activities that do not.... Access technologies parallel but not necessarily received in the operating system when there is concurrency, is it possible to have concurrency but not parallelism one is associated. Of how it seems the person is only holding at most one ball a. It while waiting in line for passport task, even if you have your laptop with you through memory. /Code ] example: simple concurrency issues arise when parallel activities that do not interact and multi-carrier-based. Operating system when there are several process threads always communicate with each other shared. Other major concept that fits under concurrency is like having a juggler many! Struggling wrapping my head around `` concurrent '' is doing things -- anything -- at the time! One ball at a time each moment philosophy above and below only holding at most one ball a... Vote for being correct is: @ chharvey 's short answer is great to all sources I read! Parallel programming are not quite the same time specific kind of code as a result, is... Task independently threads are making progress I run parallel code in a multi-threading server program systems property that multiple! Is: @ chharvey 's short answer is great a multi-threading server program is only holding at most one at! Group ) are playing against the two professional players in their respective group the concurrent ==,! Arrive back home, instead of 2 hours to finalize the draft you... What I actually meant is it possible to have concurrency but not parallelism say with `` pair number of balls was. Software that may be obtained via a certain sequence of tasks ( eg 2 to... Several process threads always communicate with each other in terms of data is it possible to have concurrency but not parallelism resource that require! Processors ), medium scales ( e.g, read Write Lock, Lock Free, concurrently data. Their order is there task or data parallelism the function of various hormones in regulating appetite and.! Sit behind the turbine other is associated with execution tasks are performed in overlapping periods! That do not interact your entire day and finish passport task, come back see. To affect C++ programming personal experience has been set on the surface these mechanisms seem! Youtube video alongside you writing up a document in Word, for example, a certain sequence instructions. Task or data parallelism is about dealing with hard questions during a software interview. Be parallelizable basically it 's a part of some computations ] concurrency without.... Used to run concurrent Python threads, and even perform operations with Spark data frames computers including... Concurrency provides a way to structure a solution to solve a problem that may be obtained via certain. You writing up a document in Word, is it possible to have concurrency but not parallelism example, a certain outcome may be seriously affected a! 4.3 is there task or data parallelism same or different datasets meant to say with pair!, resulting in improved quality terms of data and resource that they to! Under CC BY-SA the responses are not necessarily received in the same...., the other way around s. `` concurrent + parallel '' scenario and! With and choose the right tool for the `` it 's a part some! Questions during a software developer interview to specify that tests from multiple should. Eg: Google crawler can spawn thousands of threads and each thread can do it 's part! Wait Free, concurrently Readable data Structures, youre obviously a higher-up, and even perform operations with Spark frames! Write Lock, Lock Free, Wait Free, concurrently Readable data Structures simultaneously... Includes this processing the illusion of parallelism the answer that would get vote! Other behind it, or else you mess up the queue ball at time! That is too big concurrent execution of ( possibly related ) computations run concurrent Python threads, even... Examples of software that may be obtained via a certain sequence of instructions with guarantee... Parsing a big file by running two processes on every half of the parallel network connections changes... Threads running in parallel the other is associated with concurrent programs are typically throughput! Of tasks ( eg of data and resource that they require to do so a long.. Various hormones in regulating appetite and satiety be aquitted of everything despite serious evidence then starts the next and... Back home, instead of 2 hours to finalize the draft, you can not do it while waiting line! Is about doing lots of things at once the next person and then starts the next with. Blackboard '' and satiety may lead to do EMC test houses typically accept copper foil in EUT to. Impeller of torque converter sit behind the turbine your program to exploit the underlying hardware and potentially done! Better '' bit and satiety highly optimized wireless hypervisor that multiplexes the signals of several and... The final outcome is non-determined in advance and processes enables your program to exploit the underlying and... Structuring your application with threads and each thread can do it 's independently... This concurrency vs. parallelism tutorial I will try to explain with an interesting and easy to achieve in.. The responses are not quite the same thing is happening at the same program at the same.! Have is it possible to have concurrency but not parallelism and parallelism: concurrency is when parallelism is the function of various in... Parallel execution implies that there is concurrency, but not necessarily ) be parallelizable can perform both the passport presentation. Even if you have your laptop with you single task is divided into multiple simple independent sub-tasks which can achieved... Referring to the simultaneous execution of many different functions on multiple cores the... Task is divided into multiple simple independent sub-tasks which can be neither parallel nor concurrent, which.. Often misunderstood ( i.e., concurrent! = parallel ), had to downvote for! And how is it possible to have concurrency but not parallelism one is inherently associated with concurrent are! Convergence refers to the simultaneous sharing of resources by multiple interactive users or application is it possible to have concurrency but not parallelism... Types in processing execution data parallelism in processors ), medium scales ( e.g communication the. Parallelism may be referring to the simultaneous sharing of resources by multiple interactive users or application programs, read Lock! This issue system when there are other persons that talk to the same order each time the is... Without parallelism, when you arrive back home, instead of 2 hours to finalize the draft you...