I'd say yes, as there must have been multiple countries that did just fine being socialist -- where socialism didn't necessarily 'fail'. Vietnam is a socialist state, as you can see on Wikipedia: https://en.wikipedia.org/wiki/List_of_socialist_states
I assume you mean communist states, though. In that case, I would say that no country has ever been able to hold onto communism, simply because communism does not go well with large urban environments. Communism is most useful in agrarian societies, of which there technically are none nowadays.
Canada has an efficient, free public healthcare system. Public school is 100% state-paid until you start post-secondary education (which lots of people don't even do). They even pay half of the cost of private schools and scholarship for college and university is very accessible. If this isn't a form of socialism, I don't know what is.
Socialism in the past hasnt been true socialism, rather its just been Government run capitalism. In the future, probably not in the next 10 years but im talking the next 40-50 years more and more people will be unemployed and will need social welfare programs, government healthcare, and free education because there will be less and less minimum wage and lower wage jobs as machines began to take the jobs of factory workers, farmers, customer service jobs, and other lower wage jobs. Eventually a buisness will develop and mass produce a machine that will take your order at mcdonalds or another fast food resturant, cook it, and serve it to you. Bang right there we have thousands of jobs lost because of that, and buisness owners will buy the machines because they wont have to pay them hourly wages and provide them with healthcare etc.. There will end up being millions of unemployed people because there are no jobs out there for them. Now we will always need engineers and buisness owners but as we progress into the future education costs will need to be lowered so people can get that engineering degree. Thats why free education is very important. So when those millions of people are unemployed, they will need welfare, healthcare, and housing to suit all there basic unealiable rights as a human being. Life liberty and property or pursuit of happiness. And when the huge anti socialist argues and says THOSE BUMS ARENT ENTITILED TO WHAT IVE EARNED, i say well there are no jobs, and they cant afford the education that you got because they werent raised in a family as wealthy as yours, so what are we going to do? Let them die? Let them lose their inealible rights as a human being of LIFE, LIBERTY, and PROPERTY? You are the ones arguing that we should stick to the constitution, and that is in the constitution. So in answer to the question has socialism ever been succsessful, id say there have only been glimpses of "true socialism" but in the future we will need to adopt more socialistic policies or else millions of people could end up dying.
The USSR(Union of Socialist Soviet Russia) which implemented such political systems eventually collapsed in 1991 which the Russian Federation was formed which embraced a market economy which significantly increased the living standards of the Russian People. Countries such as Poland, Czech Slovakia and East Germany implemented a democratic society in which East Germany merged with West Germany to create the Federation of Germany which its constitution is under a democratic Government. Countries now which have the term Socialist or People's Republic all have a market economy which is not a socialist country. An example is People's Republic of China which its economy embraces western companies to create factory in China which made the PRC one of the most powerful economy in the world. Vietnam also has an market economy similar to the PRC. DPRK(Democratic People's Republic of Korea) is under a constitution which states that it is a "Communist country" which in reality it is an modern Dictatorship more extreme than Hitler's Nazi Germany. In conclusion, all nations around the world has given up a closed market which is socialism and has fully embraced capitalist economy.
Let me paint you a picture. Hitler pre-1938 would have been considered one of the greatest leaders in the history of the world. Hitler pre-1942 had run an extremely successful attack and was sitting pretty. Of course what happened afterwards is important since he lost it all and now is considered the one of the worst leaders of all time.
Socialism works the same way in that it looks great for a moment but in reality when given the full length of time has failed 100% of the time. Argentina was a juggernaut economy in the early 1900's but since is socialist regimes isn't even in the top 20 of GDP worldwide. Japan declared itself the welfare state decades ago and it looked successful. But the last 20 years have shown their true colors as they have had almost no economic growth and their debt is the highest in the world.
China was essential socialist just a different kind and if you know anything about history they were widely known as the most powerful country in the world for 2000 years but in the 60's and 70's were the poorest in the world until they implemented free market policies which have resurrected the country and has made them much stronger.
North Korea vs South Korea. Social state vs free state which one has been successful? Cuba came to power as a social state. The examples are endless.
Now people say "well communism is different from socialism" but here is the funny thing every single communist movement originated as a welfare movement to help the poor workers. So Socialism often leads to communism which means it rightfully is included in the conversation of the results of social movements.
If you have time read this and you will be blown away at how workers rights parties can be very dangerous. https://en.wikipedia.org/wiki/Nazi_Party