Frequently Asked Questions

Exactly how Tinder delivers their suits and messages at measure

Exactly how Tinder delivers their suits and messages at measure


Up until not too long ago, the Tinder software carried out this by polling the servers every two mere seconds. Every two mere seconds, people who had the application start tends to make a request only to see if there is everything newer — almost all the amount of time, the solution got “No, little newer available.” This design operates, and has worked better because Tinder app’s beginning, nonetheless it had been time for you use the next thing.

Desire and plans

There are many disadvantages with polling. Mobile data is needlessly consumed, you’ll need most servers to manage a great deal empty site visitors, and on typical genuine posts keep returning with a single- second delay. However, it is fairly trustworthy and foreseeable. When implementing a brand new system we desired to improve on dozens of disadvantages, whilst not losing dependability. We desired to increase the real-time shipments in a manner that performedn’t interrupt too much informative post of the current structure but nonetheless offered you a platform to enhance on. Hence, Venture Keepalive came into this world.

Design and Technology

Whenever a user features a new modify (match, message, etc.), the backend provider in charge of that modify directs an email into Keepalive pipeline — we refer to it as a Nudge. A nudge is intended to be really small — think about they similar to a notification that claims, “Hi, anything is completely new!” When consumers fully grasp this Nudge, they fetch the latest information, just as before — only today, they’re certain to really get things since we notified them on the brand-new news.

We contact this a Nudge because it’s a best-effort attempt. If Nudge can’t getting provided as a result of server or community problems, it’s not the termination of the entire world; the following user up-date sends another. Into the worst case, the app will regularly sign in anyway, just to ensure it obtains the changes. Even though the application possess a WebSocket does not promise that the Nudge experience working.

In the first place, the backend phone calls the Gateway solution. This really is a lightweight HTTP provider, responsible for abstracting some of the specifics of the Keepalive program. The portal constructs a Protocol Buffer information, and is subsequently put through remaining portion of the lifecycle on the Nudge. Protobufs determine a rigid agreement and kind system, while becoming acutely light and super fast to de/serialize.

We decided WebSockets as our very own realtime distribution process. We spent energy exploring MQTT also, but weren’t satisfied with the offered brokers. The needs comprise a clusterable, open-source program that didn’t include loads of working difficulty, which, out from the gate, eradicated numerous brokers. We searched more at Mosquitto, HiveMQ, and emqttd to find out if they’d nonetheless work, but governed all of them completely as well (Mosquitto for not being able to cluster, HiveMQ for not open resource, and emqttd because launching an Erlang-based program to your backend ended up being away from scope for this venture). The wonderful benefit of MQTT is the fact that method is extremely lightweight for clients battery pack and bandwidth, and also the broker deals with both a TCP pipeline and pub/sub system all in one. Alternatively, we decided to split those duties — operating a Go provider in order to maintain a WebSocket experience of these devices, and ultizing NATS for all the pub/sub routing. Every individual creates a WebSocket with these services, which then subscribes to NATS regarding individual. Therefore, each WebSocket process are multiplexing tens of thousands of customers’ subscriptions over one link with NATS.

The NATS cluster accounts for sustaining a list of energetic subscriptions. Each consumer has exclusive identifier, which we make use of since membership subject. In this manner, every on line device a user has was paying attention to the same topic — and all of units is informed concurrently.


Probably one of the most interesting success had been the speedup in shipment. The common shipment latency using earlier program got 1.2 seconds — together with the WebSocket nudges, we slashed that as a result of about 300ms — a 4x enhancement.

The traffic to the upgrade provider — the system in charge of returning suits and information via polling — furthermore fallen significantly, which lets reduce the desired tools.

Eventually, they opens the door to other realtime properties, instance permitting us to implement typing indicators in a competent ways.

Coaching Learned

However, we encountered some rollout dilemmas besides. We discovered lots about tuning Kubernetes tools on the way. A very important factor we didn’t remember at first usually WebSockets naturally helps make a server stateful, so we can’t rapidly remove old pods — we a slow, graceful rollout process so that them cycle on naturally to avoid a retry violent storm.

At a particular level of connected users we started seeing razor-sharp increases in latency, not simply on the WebSocket; this affected all other pods as well! After per week or more of different implementation models, wanting to tune laws, and adding a whole load of metrics looking for a weakness, we ultimately discovered the reason: we were able to strike bodily variety relationship monitoring limitations. This will push all pods thereon host to queue up circle site visitors demands, which increasing latency. The rapid option was incorporating much more WebSocket pods and pressuring them onto various offers being spread-out the effect. But we revealed the main issue soon after — checking the dmesg logs, we watched lots of “ ip_conntrack: desk full; losing packet.” The actual option would be to improve the ip_conntrack_max setting to let a higher link amount.

We also-ran into a number of dilemmas across Go HTTP client that people weren’t anticipating — we necessary to track the Dialer to hold open most relationships, and always see we completely browse consumed the responses muscles, regardless of if we didn’t require it.

NATS furthermore began revealing some defects at a top scale. When every couple weeks, two offers around the cluster document each other as sluggish buyers — fundamentally, they cann’t match each other (though obtained ample readily available capacity). We increased the write_deadline allowing extra time for your network buffer to get ingested between number.

Then Actions

Given that we now have this method positioned, we’d always continue expanding onto it. A future version could eliminate the notion of a Nudge altogether, and right provide the facts — additional lowering latency and overhead. And also this unlocks different realtime features just like the typing signal.

What is Telemedicine?

Telemedicine is a service which allows health care professionals to evaluate, diagnose and treat patients using telecommunications technology.

Why should I use GoLiveDoc?

GoLiveDoc offers 24/7 medical consultations with board-certified doctors. You can use our platform from where you live, work or when you travel in the US. We also offer 24/7 behavioral health counseling for no additional fee. Health records are kept private and secure in order to protect your personal information.

How does GoLiveDoc Help?

GoLiveDoc gives you 24/7 access to board-certified doctors through secure online video or phone consultations – anytime, anywhere. GoLiveDoc is a low-cost, convenient alternativ e to Urgent Care visits or waiting several days to get an appointment with your Primary Care Physician for non- emergency medical conditions. Our doctors can diagnose your symptoms, recommend treatment […]

What happens after I complete the checkout process?

Once you have selected your plan and completed the checkout process, you will receive an email with your login credentials for the customer portal. You can use the customer portal to schedule appointments, update your electronic health records, see your consultation history or add dependents to your account.

How much does GoLiveDoc Cost?

The monthly membership fee ranges from $9.95 to $39.95 (depending on the plan you choose). The consultation fee is only $35. You can cancel your membership at any time for any reason.

If I have insurance, do I still need to pay the membership fee?

GoLiveDoc charges all members a small monthly fee.

How do I cancel my membership?

You can cancel your membership at any time for any reason. To cancel your membership, please call (888) 386-1037 or send an email to [email protected]

Does a patient have to meet with a provider in-person before a telemedicine consultation can be scheduled?

No, an in-person visit is not required before a visit can be conducted via telephone or video.

What does GoLiveDoc Treat?

We treat a variety of medical conditions. Common conditions we prescribe medication for are Cold & Flu, Pink Eye, Skin Irritation/Rash, Urinary Tract Infection, Diarrhea, Stomach Virus, Fever, Headaches and Sore Throat.

Are there Medical Conditions GoLiveDoc Cannot Treat?

There are some medical conditions that our doctors are unable to treat, including but not limited to: Broken Bones, Chronic Diseases, Erectile Dysfunction, Genital Herpes, Hair Loss, Hot Flashes, Premature Ejacuation, Smoking Cessation, STD Testing.

Can I be turned down for a pre-existing condition?

No, members are not turned away because of pre-existing conditions. GoLiveDoc is not an insurance.

Can GoLiveDoc Treat Emergencies?

GoLiveDoc Is Only For Non-Emergency Medical Issues Members Should Not Use It If They Are Experiencing A Medical Emergency. Please Dial 911 If You Are Having A Medical Emergency. GoLiveDoc Is Also Not Intended To Replace A Member’s Primary Care Physician.

Is GoLiveDoc For Emergency Situations?

GoLiveDoc Is Only For Non-Emergency Medical Issues Members Should Not Use It If They Are Experiencing A Medical Emergency. Please Dial 911 If You Are Having A Medical Emergency. GoLiveDoc Is Also Not Intended To Replace A Member’s Primary Care Physician.

Can I use it for my family?

The primary member and 7 immediate family members or household members will have access to consults. 

Do I talk to “real doctors”?

Yes. Members only talk to actual doctors who are state-licensed family practitioners, primary care physicians, internists and pediatricians. When members request a consult, they will be connected with a doctor licensed and practicing in their state.

What Type Of Doctor Or Specialist Can I Speak With?

Members Can Talk To A Doctor Directly. Our Doctors Are Licensed In Internal Medicine, Family Medicine And Pediatrics. A Doctor May Also Provide Guidance On The Type Of Specialist A Member Should See.

Can GoLiveDoc prescribe medications?

Yes, GoLiveDoc can prescribe medication for non-controlled substances. A list of controlled substances can be found here.

Are there Medications GoLiveDoc Cannot Prescribe?

We do not prescribe controlled substances and medications that would require in-person examinations, e.g. Antidepressants, birth control, medical marijuana, stimulants such as Adderall and Ritalin, narcotics or sedatives. Our Counselors cannot prescribe medications for mental health purposes.

Does GoLiveDoc Offer Access To Mental Health Professionals?

All Membership Plans Include 24/7 Behavioral And Mental Health Counseling. All Of Our Counselors Have A Master’s Degree And At Least 12 Years Of Experience.

Is there an extra fee to access mental health professionals?

There is no additional fee to speak with mental health professionals.

How does GoLiveDoc handle bloodwork, imaging, labs and other tests?

You can upload all bloodwork, imaging, labs and other tests to our secured portal for our doctors to view to help with diagnosing and treating your medical conditions.

Is My Electronic Health Record Kept Private?

Health Records Are Kept Private And Secure In Order To Protect Members’ Personal Information. Only Members Can Determine Who Can See The Information In Their Records.